JP2002011788A - Polyester film for lamination - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film for lamination, which is excellent in not only environmental property but also in the protection as well as the workability of a pattern surface and a pigmented surface. SOLUTION: The stress upon 100% extension in the lengthwise direction (F100MD [Mpa]), the stress upon 100% extension in the widthwise direction (F100TD [MPa]) and the film thickness (d[μm]) at 25 deg.C of the polyester film for lamination satisfy the formulae of F100MD<=150 (I), F100TD<=150 (II), 6,000<=F100MDXd<=25,000 (III) and 6,000<=F100TDXd<=25,000 (IV).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to metal, wood, paper,
The present invention relates to a polyester film used for decoratively covering the surface of a resin or the like. For more information,
The present invention relates to a bonding polyester film suitable as a surface material for furniture, building materials (such as wall materials), home appliances, and electronic devices (such as switches).

[0002]

2. Description of the Related Art Conventionally, as a decorative sheet used for decorative coating of the surface of metal, wood, paper, resin, etc., a polyvinyl chloride film is typical and has been preferably used in view of workability. . On the other hand, the film has a problem of toxic gas generation when the film is burned due to a fire or the like,
There are problems such as bleed-out of plasticizers, and new materials have been demanded in recent years due to needs for environmental resistance.

[0003] However, a decorative plate simply laminated with a conventional polyester film or the like is not suitable for workability after lamination, for example, bending.

On the other hand, for example, Japanese Patent Application Laid-Open No. 3-6762
No. 8 proposes a biaxially stretched polyester film for molding having improved workability at 150 ° C. However, the relationship between film thickness and workability is unknown, and further improvement in workability at room temperature has been strongly desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and is not only excellent in environmental performance, but also excellent in protection of a picture surface and a colored surface and excellent workability. An object of the present invention is to provide a polyester film for bonding.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the polyester film for laminating according to the present invention comprises:
The stress at 100% elongation in the longitudinal direction of the film at 5 ° C. (F
100 MD [MPa]) and stress at 100% elongation in the width direction (F100TD [MPa]) and film thickness (d
[Μm]) satisfying the following conditional expressions I to IV. F100MD ≦ 150 ··· (I) F100TD ≦ 150 ··· (II) 6000 ≦ F100 MD × d ≦ 25000 ··· (III) 6000 ≦ F100 TD × d ≦ 25000 ··· (IV)

In this laminating polyester film, it is preferable that the plane orientation coefficient (fn) and the film thickness (d [μm]) of the film satisfy the following conditional expressions V and VI. 0.08 ≦ fn ≦ 0.145 (V) fn ≦ 0.001 × d + 0.06 (VI)

The elongation at break at 25 ° C. is preferably at least 220%. Furthermore, the surface wetting tension is 50m
It is preferably at least N / m.

Such a polyester film for lamination according to the present invention can be used for metal, wood,
It is suitable as a coating material for surface decoration such as paper and resin, and can be suitably used particularly as a surface material for building materials such as wall materials.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail. The polyester in the present invention is a general term for a high molecular weight substance constituted by an ester bond. Examples of the dicarboxylic acid component used for this ester bond include terephthalic acid, isophthalic acid,
Naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfondicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodium sulfoisophthalic acid, aromatic dicarboxylic acids such as phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, Aliphatic dicarboxylic acids such as maleic acid and fumaric acid, alicyclic dicarboxylic acids such as cyclohexyne dicarboxylic acid, and oxycarboxylic acids such as p-oxybenzoic acid can be used. Among these, in the polyester of the present invention, the proportion of terephthalic acid to be contained is preferably 95 mol% or more from the viewpoint of heat resistance and productivity.

On the other hand, as the glycol component, for example, ethylene glycol, propanediol, butanediol,
Aliphatic glycols such as pentanediol, hexanediol and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, aromatic glycols such as bisphenol A and bisphenol S, and diethylene glycol can be used. In addition, two or more of these dicarboxylic acid components and glycol components may be used in combination.

Further, as long as the effects of the present invention are not impaired, it is also possible to use a copolymerized polyester obtained by copolymerizing a polyfunctional compound such as trimellitic acid, trimesic acid, and trimethylolpropane.

It is preferable to use a blend of two or more of the above polymers in order to improve processability. Among them, a mixed polymer obtained by blending polyethylene terephthalate with polytrimethylene terephthalate and / or polybutylene terephthalate is particularly preferred from the viewpoint of flexibility.

The melting point of the polyester film in the present invention is preferably from 220 to 2 from the viewpoint of heat resistance and workability.
70 ° C., more preferably 240 to 270 ° C., particularly preferably 246 to 270 ° C. In particular, when the melting point is less than the above range, heat resistance is inferior. Therefore, when exposed to a high temperature during a processing step or during use, a problem may occur, which is not preferable. Here, the melting point of the polyester film is a so-called differential temperature calorimetry (DSC).
Is the endothermic peak temperature at the time of melting detected at the time of the first temperature rise (1st Run).

The polyester film of the present invention is desirably biaxially stretched from the viewpoint of heat resistance and dimensional stability. Such a biaxial stretching method may be any of simultaneous biaxial stretching and sequential biaxial stretching. At this time, simultaneous biaxial stretching is particularly preferable from the viewpoint of suppressing uneven thickness.

The polyester film of the present invention can be prepared by using different kinds of polyesters, for example, as disclosed in JP-A-9-245.
No. 88, it can be a laminated structure. The form of the laminated film is not particularly limited, and examples thereof include A / B, B / A / B, and C / A / B lamination.

The total thickness of the polyester film for lamination of the present invention is preferably 50 to 500 μm, more preferably 50 to 500 μm, in view of moldability, coatability on a substrate, protection of the surface of the substrate, and design. 60-300 μm,
Particularly preferably, it is 70 to 200 μm.

In the polyester film for lamination according to the present invention, one of the lengthwise and widthwise directions of the film at 25 ° C.
00% elongation stress (F100MD [MPa] and F10
0TD [MPa]) and film thickness (d [μm])
However, it is necessary that both satisfy the following conditional expressions I to IV. F100MD ≦ 150 ··· (I) F100TD ≦ 150 ··· (II) 6000 ≦ F100 MD × d ≦ 25000 ··· (III) 6000 ≦ F100 TD × d ≦ 25000 ··· (IV)

More preferably, F100 of formulas I and II is 140 MPa or less, particularly preferably 130 MPa
a or less. Also more preferably, Formulas III and IV
F100 × d is in the range of 7000 to 20,000,
It is particularly preferably in the range of 8,000 to 18,000.

In the present invention, the plane orientation coefficient (fn) and the film thickness (d [μm]) of the film are determined from the viewpoint of processability.
It is preferable to satisfy the following conditional expressions V and VI. 0.08 ≦ fn ≦ 0.145 (V) fn ≦ 0.001 × d + 0.06 (VI)

At this time, fn is more preferably 0.0
It is 9 to 0.14, particularly preferably 0.1 to 0.135. The plane orientation coefficient (fn) is defined by the following formula IX based on the refractive index in the longitudinal direction (Nx), the refractive index in the width direction (Ny), and the refractive index in the thickness direction (Nz) of a film measured using an Abbe refractometer or the like. This is a calculated value. fn = (Nx + Ny) / 2-Nz (IX) At this time, if the longitudinal direction and the width direction of the film are not clear, the refractive index in the main axis direction of the orientation, the direction perpendicular to the main axis direction of the orientation, and the thickness direction is determined. The plane orientation coefficient can be obtained as Nx, Ny, and Nz, respectively.

In the present invention, the peak value of the thermal shrinkage stress in the longitudinal direction (TMD [MPa]) and the peak value of the thermal shrinkage stress in the width direction (TMD) are used to improve the adhesiveness and flatness between the film and the substrate. TTD [MPa]) and thickness (d [μ
m]) is preferably represented by the following formula. TMD × d ≦ 200 [μm · MPa] (VII) TTD × d ≦ 200 [μm · MPa] (VIII) More preferably, both TMD × d and TTD × d are 180.
Hereinafter, it is particularly preferably 150 or less.

If the ratio is out of the above range, not only is the cause of peeling due to poor adhesiveness, but also, for example, the base material is deformed. Absent.

As a specific means for achieving the formulas VII and VIII, the stretching is performed at a temperature of from 180 to 260 ° C., more preferably from 190 to 260 ° C., while relaxing at least 5%, more preferably at least 7% after stretching. Preferably 200
C. to 260.degree. C., or preheating at 95 to 120.degree. C. before stretching, formulas I and I
Examples of the method include a method of reducing the thickness as long as the condition of I is not deviated, a method of using the above-mentioned copolymerized polyester and the blend polymer, and the like, but are not limited to these methods.

From the viewpoint of workability, the elongation at break at 25 ° C. is preferably 220% or more, more preferably 25% or more.
0% or more.

190 ° C. of the polyester film of the present invention
Is preferably 10% or less, more preferably 5% or less in both the longitudinal direction and the width direction of the film.
It is particularly preferably at most 3%.

The thickness unevenness of the film is preferably 15
%, Particularly preferably 10%, from the viewpoint of printability, workability and the like.

The film of the present invention has a surface wetting tension of 50 from the viewpoints of printability, processability, adhesion and the like on the film.
It is preferably at least mN / m, more preferably at least 56 mN / m.

A film having a wet surface tension of 50 mN / m or more can be achieved by performing a surface treatment, for example, a corona discharge treatment, a plasma treatment, a flame treatment, an ultraviolet irradiation treatment, an electron beam irradiation treatment, a chemical treatment, Examples include physical surface roughening treatment and surface coating treatment, but are not particularly limited as long as the effects of the present invention are not impaired. Among them, corona discharge treatment is a simple and effective method, and can be preferably performed.

The film of the present invention may be coated with various coatings.
There is no particular limitation as long as the effects of the present invention are not impaired.

In the present invention, the 60-degree specular gloss of the film is preferably 60% or more from the viewpoint of aesthetics after printing.
It is particularly preferably at least 90%.

Further, the haze inside the film is preferably not more than 35% from the viewpoint of the beauty of the decorative plate.
Further, it is particularly preferably at most 15%. If the internal haze exceeds the above range, the pattern and coloring become unclear when used as a decorative board, which is not preferable.
In addition, there is no particular lower limit to the preferable value of the internal haze,
For example, in the case of a polyethylene terephthalate film having a thickness of about 100 μm, when it is low, the content is about 0.5%.

Further, it is preferable that the increase rate of the internal haze after heat treatment at 190 ° C. for 10 minutes is small, preferably this increase rate is preferably 40% or less, particularly preferably 20% or less.
% Or less. If it exceeds 40%, whitening during processing becomes remarkable, which is not preferable.

In the present invention, from the viewpoint of improving the adhesiveness and processability between the film and the substrate, the carboxyl end group content is
Preferably 20 to 60 equivalents / ton, more preferably 3
Those having 0 to 50 equivalents / ton are preferred.

In the present invention, the intrinsic viscosity of the polyester is preferably 0.50 dl / g or more, more preferably 0.55 d / g, in order to further improve the adhesiveness and the film-forming stability.
Those having a l / g or more, particularly preferably 0.60 dl / g or more, are used. If the intrinsic viscosity is less than 0.50 dl / g, the adhesiveness is undesirably reduced.

The catalyst for producing the polyester of the present invention is not particularly limited, but includes alkaline earth metal compounds, manganese compounds, cobalt compounds, aluminum compounds, antimony compounds, titanium compounds, titanium / silicon composite oxides, and germanium compounds. Etc. can be used.
Among them, a titanium compound, a titanium / silicon composite oxide, and a germanium compound are preferable in setting the catalytic activity, taste characteristics, and the amount of the catalytic metal.

For example, when a titanium / silicon catalyst is added as a catalyst, a terephthalic acid component and an ethylene glycol component are reacted, and then a titanium / silicon composite oxide and a phosphorus compound are added. And a method of obtaining a polyester having a specific amount of a catalytic metal and a specific amount of phosphorus by a polycondensation reaction until the content of diethylene glycol reaches the above.

The phosphorus compound added as a heat stabilizer is not particularly limited, but phosphoric acid and phosphorous acid are preferred.

The polyester film of the present invention can be used to improve the beautifulness, weather resistance, and discoloration resistance of a printed board in extremely good condition. It is preferable that the relationship between the residual amount (P: unit mmol%) satisfies the following formula X. 0.3 ≦ M / P ≦ 5 (X) Further, when the value of M / P is 3 or less, both the productivity and the thermal stability of the film become good, which is particularly preferable.

The method for producing the polyester film in the present invention is not particularly limited. For example, after drying the polyester as required, it is supplied to a known melt extruder, extruded into a sheet shape from a slit die, and subjected to static molding. This is a method in which the unstretched sheet is stretched after being brought into close contact with the casting drum by cooling, solidified by cooling, obtaining an unstretched sheet. Such a stretching method may be any of simultaneous biaxial stretching and sequential biaxial stretching,
In short, a method is employed in which the unstretched sheet is stretched and heat-treated in the longitudinal direction and the width direction of the film to obtain a film having a desired degree of plane orientation. Among these methods, a tenter method is preferable in terms of film quality. After stretching in the longitudinal direction, stretching in the width direction is preferred.
Alternatively, a sequential biaxial stretching method in which the film is stretched in the width direction and then stretching in the longitudinal direction, and a simultaneous biaxial stretching method in which the film is stretched almost simultaneously in the longitudinal direction and the width direction are desirable.

The stretching ratio of the biaxial stretching is 1.6 to 4.2 times, preferably 1.7 to 4.2 times in each direction.
It is 4.0 times. In this case, the stretching ratio in the longitudinal direction or the width direction may be increased, and may be the same. The stretching speed is preferably from 1000% / minute to 200,000% / minute, and the stretching temperature may be any temperature as long as it is equal to or higher than the glass transition temperature of the polyester and equal to or lower than the glass transition temperature + 100 ° C. 80-17
Stretching is preferably performed in the range of 0 ° C. Further, the film is subjected to a heat treatment after the biaxial stretching, and this heat treatment can be carried out by any conventionally known method such as in an oven or on a heated roll. The heat treatment temperature can be any temperature between 120 ° C. and 245 ° C., but is preferably between 120 and 240 ° C. Further, the heat treatment time can be arbitrarily set, but is preferably 1 to 60 seconds. The heat treatment may be performed while relaxing the film in the longitudinal direction and / or the width direction.
Furthermore, re-stretching may be performed once or more in each direction, and then heat treatment may be performed.

The polyester has an average particle size of 0.0
Particles arbitrarily selected from known internal particles of 1 to 10 μm, external particles such as inorganic particles and / or organic particles can be contained. The use of particles having an average particle diameter of more than 10 μm tends to cause defects in the film, which is not preferable in terms of design.
Examples of such known particles include inorganic particles such as wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, clay, and hydroxyapatite, and styrene, silicone, and acrylic. Organic particles containing acids and the like as constituent components can be used. Of these, inorganic particles such as dry, wet and dry colloidal silica and alumina, and organic particles containing styrene, silicone, acrylic acid, methacrylic acid, polyester, divinylbenzene and the like as constituents are preferably used. Two or more of these internal particles, inorganic particles and / or organic particles may be used in combination as long as the properties are not impaired.

Further, the addition amount of these particles is preferably in the range of 0.01% by weight to 50% by weight. 0.01
If it is less than 10% by weight, film winding becomes difficult, which is not preferable in handling. On the other hand, if it exceeds 50% by weight, it is not preferable because it causes coarse projections and deterioration of film forming properties.

The polyester film for lamination of the present invention can be used as a decorative board for laminating on metal, wood, paper, resin and the like. More specifically, after providing a pattern layer or a colored layer by printing or the like on the surface of these materials, they are used by bonding them via heat bonding or an adhesive, or a pattern layer or a colored layer is printed on the film of the present invention by printing or the like. It can be used by attaching the picture layer or the colored layer side to various plate materials. Further, the composite material thus obtained may be used as a decorative board as it is, or the composite material may be further used as a decorative board by pasting it to another material.

Examples of the adhesive include a urea resin adhesive, a melamine resin adhesive, a phenol resin adhesive, an α-olefin resin adhesive, an adhesive made of a mixture of an aqueous polymer and an isocyanate, and an epoxy adhesive. adhesive,
Solution type vinyl acetate resin adhesive, emulsion type vinyl acetate resin adhesive, acrylic emulsion adhesive, hot melt adhesive, cyanoacrylate adhesive, polyurethane adhesive, chloroprene rubber adhesive, nitrile rubber adhesive Adhesives, SBR adhesives, modified rubber emulsion adhesives, ethylene copolymer resin adhesives, resorcinol adhesives, natural rubber adhesives, cellulose adhesives, starch pastes, dextrins, and the like.

The resin to be bonded is not particularly limited, but various thermoplastic resins and thermosetting resins can be used.

The metal to be bonded is not particularly limited, but a metal made of iron, aluminum or the like having good workability can be preferably used. May be provided with a known inorganic oxide coating layer and a metal plating layer.

The polyester film for lamination of the present invention can be used after being subjected to various surface treatments such as embossing and printing before or after lamination. Further, in the case of the polyester film for decorative board, it is laminated to the substrate. Thereafter, forming according to the purpose, such as bending and compression, can be performed. Further, various forming processes such as vacuum forming, pressure forming, in-mold forming, and the like can be performed according to the purpose. These molded products are used as surface materials for furniture, building materials (wall materials, floor materials, laminated steel plates, etc.), housing equipment, electronic equipment (switches, buttons, nameplates, etc.), and process films ( Surface protection film, transfer in-mold film, etc.).

[0049]

The present invention will be described in detail with reference to the following examples. The characteristics were measured and evaluated by the following methods.

(1) Melting point (° C.) 5 mg of a film was sampled and measured by a differential scanning calorimeter (RDC220) manufactured by Seiko Instruments Inc.
The measurement was performed at a heating rate of 10 ° C./min, and the peak temperature of melting was defined as the melting point. In particular, when a plurality of melting peaks appeared, the lower one was regarded as the melting point.

(2) Intrinsic viscosity Polyester is dissolved in orthochlorophenol,
Measured in ° C.

(3) Plane Orientation Coefficient Using a sodium D line (wavelength: 589 nm) as a light source, using a Abbe refractometer, the longitudinal refractive index (N
x), refractive index in the width direction (Ny), refractive index in the thickness direction (Nz)
Was calculated from the following formula IX. fn = (Nx + Ny) / 2-Nz (IX)

(4) Stress at 100% elongation and elongation at break A sample having a length of 150 mm and a width of 10 mm was cut out from the biaxially stretched film, and the sample was subjected to an initial length of 50 mm and a tensile speed using a tensile tester manufactured by Orientec. 300m
m / min, pulled at 25 ° C, and the resulting load-
The stress at 100% elongation and the elongation at break in each direction were determined from the strain curve.

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

(6) Workability The film having one side printed was bonded via an adhesive such that a steel plate having a thickness of 0.8 mm was in contact with the back surface of the printed surface of the film. At this time, when using a film having one surface subjected to a corona discharge treatment, the treated surface was an adhesive surface, and the back surface was a printing surface. The resulting composite material is angled 90
° Bending, and the state of the film at the corner at that time was visually confirmed. ◎: Cracks, whitening, breakage, and peeling were not observed in the bent portion, and the appearance was extremely good. ：: Although slight whitening is observed at the bent portion, there is no problem in appearance. ×: Any of cracks, whitening, breakage and peeling was observed in the bent portion, and the appearance was extremely poor.

(7) Beauty The surface of the material after the lamination was observed, and the sharpness of the print was visually confirmed. ◎: Extremely clear. ：: The sharpness is slightly lacking, but there is no unevenness in printing and there is no problem in appearance. X: The printing is uneven and the appearance is extremely poor.

(8) Heat Shrinkage Stress Thermomechanical Analyzer (TMA / S manufactured by Seiko Electronic Industry Co., Ltd.)
S6100) at a heating rate of 10 ° C./min.
A constant length measurement was performed under the conditions of a sample length of 20 mm and a sample width of 4 mm, and the peak value of the heat shrinkage stress in the longitudinal direction was determined by TMD [MP
a], the TTD [MP
a].

Example 1 In Example 1, phosphoric acid and wet silica (0.08% by weight) were added as a magnesium compound and antimony compound catalyst to polymerize polyethylene terephthalate (intrinsic viscosity 0.65 dl / g, carboxyl terminal) Base 25
Equivalent / ton, M / P = 2.5). After vacuum drying the obtained polyester at 180 ° C. for 4 hours, it is supplied to a melt extruder,
The sheet was extruded into a sheet form from a slit-shaped die, closely adhered to a mirror-surface cooling drum by applying static electricity (3.0 kV), and cooled and solidified to form an unstretched sheet. This unstretched sheet is first stretched 3.0 times in the longitudinal direction with a roll heated to a temperature of 105 ° C., and further stretched in the width direction at a stretching temperature of 127 ° C.
After stretching one time, at 195 ° C., 5% relaxation in the width direction,
Heat treatment was performed for 6 seconds to obtain a biaxially stretched polyester film having a thickness of 100 μm. One side of the obtained film was subjected to corona discharge treatment and evaluated. The resulting film showed very good properties as shown in Table 1.

Example 2 In Example 2, a film was formed under the same conditions as in Example 1 except that the stretching conditions were changed as shown in Table 1. The characteristics were as shown in Table 1, and were characteristics that could be used in practical use.

Example 3 In Example 3, 10 mol% of isophthalic acid copolymerized polyethylene terephthalate polymerized by adding phosphoric acid and wet silica (0.08 wt%) using a germanium compound as a catalyst (intrinsic viscosity: 0.63 dl / g, carboxyl end group 3
8 equivalents / ton, M / P = 2.1), and a film was formed under the stretching conditions shown in Table 1. Table 1 shows the obtained films.
As shown in the above, excellent properties were exhibited particularly in workability.

Example 4 In Example 4, 90 parts by weight of the polyethylene terephthalate and 10 parts by weight of polytrimethylene terephthalate used in Example 1 were polymerized using a titanium compound as a catalyst, phosphoric acid was added, and the intrinsic viscosity was 0.9 dl. / G, 10 equivalents / ton of carboxyl end group, M / P = 6), dried and supplied to an extruder to form a film. As shown in Table 1, the properties of the obtained film were particularly excellent in processability.

Example 5 In Example 5, a film was formed under the same conditions as in Example 1 except that the relaxation under the transverse stretching condition was 7% and the heat treatment temperature was 230 ° C. Table 2 shows the properties of the obtained film.
As shown in the above, it is excellent in workability, beauty, etc.,
The appearance, such as the adhesion of the film and the flatness of the bonded steel sheet, was particularly good.

In Examples 1 to 5, when the bonded steel sheets were subjected to a hot air treatment at 210 ° C. for 30 seconds, the printed state did not change in Examples 1, 2 and 5, but in Examples 3 and 4. Printing spots occurred.

Comparative Example 1 In Comparative Example 1, a film was formed under the same conditions as in Example 1 except that the stretching conditions were changed as shown in Table 2. The characteristics were as shown in Table 2 and the workability was poor.

Comparative Example 2 In Comparative Example 2, phosphoric acid and wet silica (0.2% by weight) were used as the magnesium compound and antimony compound catalysts.
Was added to polymerize polyethylene terephthalate (intrinsic viscosity 0.65 dl / g, carboxyl end group 25 equivalents / ton, M / P = 6). Film formation was performed using the obtained polymer under the stretching conditions shown in Table 2, and the obtained film was evaluated. Both processability and beauty were very poor.

[0066]

[Table 1]

[0067]

[Table 2]

The symbols in Tables 1 and 2 are as follows. PET: polyethylene terephthalate PET / I ¹⁰ : 10 mol% copolymerized polyethylene terephthalate isophthalic acid PTT: polytrimethylene terephthalate F100: stress at 100% elongation (25 ° C.) [MPa] TMD: peak value of heat shrinkage stress in the longitudinal direction [ μm ・ MP
a] TTD: Peak value of heat shrinkage stress in the width direction [μm · MP
a]

[0069]

The film for bonding according to the present invention is excellent in processability by controlling the stress at the time of 100% elongation in the longitudinal direction and the width direction of the film by using a material excellent in environmental properties, and after bonding. A film excellent in beauty can be obtained.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Kimura 1-1-1, Sonoyama, Otsu-shi, Shiga F-term (reference) in the Shiga Plant of Toray Industries, Inc. 4F100 AK41A AT00B BA02 GB08 JA03A JA20A JK02A JK14A 4F210 AA24 AF16 AG01 RA03 RC02 RG02 RG04 RG43

Claims (6)

[Claims] 1. 100% of the length of the film at 25 ° C.
% Elongation stress (F100MD [MPa]), 100% elongation stress in the width direction (F100TD [MPa]) and film thickness (d [μm]) satisfy the following conditional expressions I to IV. Polyester film for lamination. F100MD ≦ 150 ··· (I) F100TD ≦ 150 ··· (II) 6000 ≦ F100 MD × d ≦ 25000 ··· (III) 6000 ≦ F100 TD × d ≦ 25000 ··· (IV) 2. The polyester film for lamination according to claim 1, wherein the plane orientation coefficient (fn) and the film thickness (d [μm]) of the film satisfy the following conditional expressions V and VI. 0.08 ≦ fn ≦ 0.145 (V) fn ≦ 0.001 × d + 0.06 (VI) 3. The polyester film for lamination according to claim 1, wherein the elongation at break at 25 ° C. is 220% or more. 4. The polyester film for lamination according to claim 1, wherein the surface wetting tension is 50 mN / m or more. 5. The polyester film for lamination according to claim 1, which is used as a wall material. 6. The maximum value of the heat shrinkage stress in the longitudinal direction (TMD).
[MPa]), the maximum value of the thermal contraction stress in the width direction (TTD)
The polyester film for lamination according to any one of claims 1 to 5, wherein the relationship between [MPa]) and thickness (d [μm]) is represented by the following formula. TMD × d ≦ 200 [μm · MPa] (VII) TTD × d ≦ 200 [μm · MPa] (VIII)