JP2004306401A - Laminated film for vapor deposition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film for vapor deposition capable of being thermally bonded to a support without using an adhesive which uses an organic solvent or the like, having a flat surface adapted to the formation of a vapor deposition layer and having large reflectivity and excellent in film take-up workability. <P>SOLUTION: This laminated film for vapor deposition has at least two layers, that is, a polyester layer A for constituting a surface to be vapor-deposited and a polyester layer B having thermal adhesiveness and is constituted so as to simultaneously satisfy formula (1): Ra1≤0.05 and formula (2): Ra1+Ra2≥0.015 [wherein Ra1 is the surface roughness (μm) of the layer A and Ra2 is the surface roughness (μm) of the layer B]. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４４】
【表２】

【００４５】
実施例１から３においては、蒸着した反射面における反射率も大きく熱接着性に、また巻き作業性に優れていた。特に実施例２と３は、１５０℃の熱収縮率も小さかった。一方、比較例１は、熱接着層のない単層フィルムのため、熱接着しなかった。比較例２は、表面粗さＲａ１とＲａ２の和が０．０１５μｍ未満のためフィルムの巻き作業性が悪かった。また比較例３は、層Ａの表面粗さＲａ１が０．０５μｍを超えているため、反射率が低下した。
【００４６】
【発明の効果】
本発明によれば、有機溶剤等を使用した接着剤を用いることなく支持体に熱接着することができ、蒸着層を形成する表面が平坦なため反射率が大きく、かつフィルム巻取り作業性にも優れた蒸着用貼合せフィルムが提供され、本発明の工業的価値は高い。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laminated film for vapor deposition suitable for giving a mirror-like surface appearance, and particularly to a reflector for a liquid crystal display backlight having a metal vapor-deposited surface as a light reflecting surface, and a reflective film for a fluorescent lamp or a light emitting diode. The present invention relates to a polyester film substrate that can be suitably used as a light reflection plate used for an umbrella, a road sign, and the like.
[0002]
[Prior art]
BACKGROUND ART A heat-adhesive film having a vapor-deposited layer has been used for various applications. For example, Patent Literature 1 describes that it is used for a coated metal plate for producing a molded article having a matte surface. However, since the surface roughness of the deposited layer is large and irregular reflection occurs on the surface, the light reflectivity is small. Also, for example, Patent Document 2 describes that the film is used for a packaging film having heat sealing properties and gas barrier properties. However, a film having a heat sealing property at 100 ° C. is easily peeled off from the support plate when the heat-bonded film-coated support plate is formed. May undesirably peel off from the support. On the other hand, according to Patent Literature 3, a reflective film for a liquid crystal backlight is formed by depositing a vapor-deposited layer on a film, applying an adhesive to a surface of the vapor-deposited layer opposite to the film, and drying and adhering to a support. Since the adhesive contains an organic solvent, it is not preferable for safety and health. In addition, there is a problem that the production process is complicated because there are a coating process and a subsequent drying process.
[0003]
[Patent Document 1] JP-A-58-183249 [Patent Document 2] JP-A-3-81151 [Patent Document 3] JP-A-2002-117715
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a problem to be solved is that it can be thermally bonded to a support without using an adhesive using an organic solvent or the like, and the surface on which a vapor deposition layer is formed is flat and reflective. It is an object of the present invention to provide a laminated film for vapor deposition having a high rate and excellent film winding workability.
[0005]
[Means for Solving the Problems]
The present inventor has conducted intensive studies in view of the above problems, and as a result, has found that a laminated film having a specific configuration can easily solve the above problems, and has completed the present invention.
[0006]
That is, the gist of the present invention is a laminated film having at least two layers of a polyester layer A constituting a surface to be vapor-deposited and a polyester layer B having thermal adhesiveness, and simultaneously satisfies the following formulas (1) and (2). A laminated film for vapor deposition characterized by the above.
Ra1 ≦ 0.05 (1)
Ra1 + Ra2 ≧ 0.015 (2)
(In the above formula, Ra1 means the surface roughness (μm) of the layer A, and Ra2 means the surface roughness (μm) of the layer B.)
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The polyester in the present invention includes aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalene-2,6-dicarboxylic acid, and ethylene glycol, diethylene glycol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, It is a polyester having an ester with a glycol such as 4-cyclohexanedimethanol as a main component. The polyester can be obtained by directly polymerizing an aromatic dicarboxylic acid and glycol, or by subjecting an aromatic dicarboxylic acid dialkyl ester and glycol to a transesterification reaction, followed by polycondensation, or a diglycol of an aromatic dicarboxylic acid. It can also be obtained by a method such as polycondensation of an ester. Representative examples of the polyester include polyethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate (PEN), and polybutylene terephthalate. Such a polyester may be a homopolymer which is not copolymerized, and 40 mol% or less of the dicarboxylic acid component is a dicarboxylic acid component other than the main component, and 40 mol% or less of the diol component is a diol component other than the main component. It may be a certain copolymerized polyester or a mixture thereof.
[0008]
The laminated film for vapor deposition of the present invention (hereinafter sometimes simply referred to as a film) is composed of a laminated film having at least two layers, and a polyester layer constituting a surface to be vapor-deposited is a polyester layer A (hereinafter simply referred to as a film). The layer of the present invention may have, for example, a two-layer structure of A / B or a three-layer structure of A / C / B.
[0009]
In the film of the present invention, the melting point of the heat bonding layer B (the layer constituting the exposed surface opposite to the layer A) is preferably in the range of 100 to 250 ° C, more preferably 120 to 240 ° C, and particularly preferably. It is in the range of 130 to 230 ° C. If the melting point is less than 100 ° C., the heat resistance tends to be poor, and the heat of the light source reduces the adhesive strength with the support, and the film may be displaced or peeled off from the support. On the other hand, when the melting point exceeds 250 ° C., the temperature condition of the heat bonding step is increased, and as a result, the film is likely to shrink and the bonding may be difficult. Further, particularly when the vapor deposition layer is formed of silver or an alloy containing silver, it tends to be susceptible to thermal degradation.
[0010]
The polyester constituting the heat bonding layer B preferably has a low degree of crystallization, and the degree of crystallization calculated from the density is preferably 30% or less, more preferably 20% or less. If the degree of crystallinity exceeds 30%, the adhesion to the support may be reduced and peeling may be reduced, and the temperature required for thermal bonding may increase, making thermal bonding difficult. In order to lower the crystallinity, there is a method of using a copolymer polyester having a low melting point, a method of setting the heat treatment temperature at the time of film formation to be equal to or higher than the melting point of the polyester of the heat bonding layer B, and the like.
[0011]
Specific examples of the polyester constituting the heat bonding layer include a polyethylene terephthalate copolymer polyester containing 5 to 40 mol% of an isophthalic acid unit as a dicarboxylic acid component, and 5 to 40 cyclohexane dimethanol as a diol component. Polyethylene terephthalate copolymerized polyester containing mol%.
[0012]
Further, a polymer containing a polar group may be added to the heat bonding layer in order to improve the adhesive strength with the support. Examples thereof include an epoxy group-containing polymer and a vinyl polymer. The content of these compounds in the layer B is usually 0.1 to 20% by weight, preferably 0.5 to 15% by weight. It is. When the content is less than 0.1% by weight, the effect of improving the adhesive strength tends to be small. On the other hand, when the content is more than 20% by weight, the viscosity of the melt is significantly different from that of polyester, and the film-forming property is deteriorated. Sometimes.
[0013]
In the present invention, the surface roughness Ra1 of the layer A constituting the surface to be deposited is 0.05 μm or less, preferably 0.04 or less, more preferably 0.035 or less. When the surface roughness Ra1 of the layer A exceeds 0.05 μm, irregular reflection occurs on the surface, and the reflectance decreases.
[0014]
In the present invention, the sum of the surface roughness Ra1 of the layer A constituting the surface to be deposited and the surface roughness Ra2 of the thermal bonding layer B is 0.015 μm or more, preferably 0.020 μm or more, and more preferably 0 μm or more. 0.025 μm or more. If the sum of Ra1 and Ra2 is less than 0.015, the film winding workability will be poor and the productivity will be poor.
[0015]
In order to obtain a film having the above-mentioned surface characteristics in the present invention, for example, an appropriate amount of inert particles is contained in polyester. The average particle size of the inert particles used in the present invention is preferably in the range of 0.2 to 4.0 μm, more preferably 0.3 to 3.5 μm, and particularly preferably 0.4 to 3.0 μm. Inactive particles having an average particle size of less than 0.2 μm tend to deteriorate the winding workability of the film. On the other hand, when the average particle size exceeds 4.0 μm, it may be difficult to reduce the surface roughness Ra1 of the deposition layer A to 0.015 μm or less.
[0016]
The relationship (Da / La) between the average particle diameter Da (μm) of the inert particles in the layer A and the thickness La (μm) of the layer A is preferably 2.0 or less, more preferably 1.5 or less, Especially preferably, it is 1.2 or less. When Da / La exceeds 2.0, a deposition defect may occur. The particle size distribution of the inert particles in the layer A is preferably narrow, and the particle size distribution width is preferably 1.6 or less, more preferably 1.5 or less. If the particle size distribution width exceeds 1.6, abrasion originating from the coarse projections occurs in the film manufacturing process, and a deposition defect may occur.
[0017]
Further, the relationship (Db / Lb) between the average particle diameter Db (μm) of the inert particles in the layer B and the thickness Lb (μm) of the layer B is preferably 0.1 to 4.0, more preferably 0.2. -3.5, particularly preferably 0.3-3.0. When Db / Lb is less than 0.1, the winding workability of the film tends to deteriorate, and when it exceeds 4.0, the thermal adhesiveness tends to decrease.
[0018]
The type of inert particles used is not particularly limited, and examples thereof include kaolin, talc, calcium carbonate, amorphous silica, spherical silica, and organic polymer particles. Further, two or more kinds of inert particles may be used.
[0019]
The heat shrinkage at 150 ° C. of the film of the present invention is preferably 3% or less, more preferably 2% or less, and particularly preferably 1% or less. When the heat shrinkage at 150 ° C. exceeds 3%, the shrinkage of the film at the time of heat bonding tends to increase, and uneven bonding and wrinkles may occur.
[0020]
The thickness of the film of the present invention is not particularly limited, but is usually in the range of 10 to 500 μm, and preferably in the range of 20 to 400 μm. If the film thickness is less than 10 μm, the film-forming properties of the film may be deteriorated. Further, when the film thickness exceeds 500 μm, the film productivity of the biaxially stretched film tends to decrease. The thickness of the layer B is usually in the range of 0.5 to 30 μm, preferably in the range of 1.0 to 25 μm. When the thickness of the layer B is 0.5 μm or less, the adhesiveness to the support tends to decrease. On the other hand, when the thickness of the layer B is 30 μm, the effect of improving the adhesiveness is saturated, and further improvement cannot be expected.
[0021]
The film of the present invention may contain additives such as an ultraviolet absorber, an antistatic agent, a coloring agent, an antioxidant, an antifoaming agent, and a fluorescent whitening agent, if necessary. Further, it may contain inert particles having an average particle size of 0.3 μm or less which does not greatly affect the surface roughness. If necessary, the film surface may be subjected to a coating treatment for the purpose of imparting lubricity, vapor deposition property, antistatic property, adhesive property and the like.
[0022]
Next, the method for producing the film of the present invention will be specifically described, but is not particularly limited to the following examples as long as the constitutional requirements of the present invention are satisfied.
[0023]
When producing the film of the present invention, the dried polyester forming the layer A and the dried polyester forming the layers other than the layer A are supplied to separate extruders and heated to a temperature not lower than the melting point of each polyester. To melt each. Next, the respective polyesters are extruded as a molten sheet from a T-die in a state of being laminated. Subsequently, the molten sheet is rapidly cooled to a temperature lower than the glass transition temperature on a rotary cooling drum to obtain an amorphous unstretched film. At this time, in order to improve the flatness of the unstretched film, the adhesion between the unstretched film and the rotary cooling drum may be improved by an electrostatic application adhesion method, a liquid application adhesion method, or the like. Then, the unstretched film is stretched in the longitudinal direction (longitudinal stretching) using a roll stretching machine to obtain a uniaxially stretched film. The stretching temperature at this time is in the range of minus 10 ° C. to plus 40 ° C. of the glass transition temperature (Tg) of the raw resin. The stretching ratio is preferably 2.5 to 7.0 times, and more preferably 3.0 to 6.0 times. Further, the longitudinal stretching may be performed in only one stage, or may be performed in two or more stages. Next, the biaxially stretched film is obtained by stretching (transversely stretching) the uniaxially stretched film in the width direction using a tenter stretching machine. The stretching temperature at this time is in the range of plus 50 ° C. from the glass transition temperature (Tg) of the raw resin. The stretching ratio is preferably 2.5 to 7.0 times, and more preferably 3.5 to 6.0 times. Further, the transverse stretching may be performed in only one stage, or may be performed in two or more stages. Simultaneous biaxial stretching in which vertical and horizontal directions are simultaneously performed may be performed. And a laminated film is manufactured by heat-processing a biaxially stretched film. The heat treatment temperature at this time is 130 to 250 ° C. When heat-treating the biaxially stretched film, the biaxially stretched film may be relaxed within 20%.
[0024]
In the film of the present invention, a metal such as aluminum or silver is then deposited on the surface of the layer A to form a light reflecting layer. Further, a protective layer may be applied on the evaporation layer. Next, the support is thermally bonded to the support, and the support at this time is a plate-like plastic plate or a metal plate, specifically, a steel plate, an aluminum plate, a brass plate, a copper plate, or the like. The temperature of the thermal bonding is usually in the range of 110 to 190 ° C, preferably 120 to 180 ° C.
The support to which the film is adhered is formed into a desired shape.
[0025]
【Example】
EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. The definitions of the measurement methods and terms used in the examples and the present invention are as follows.
[0026]
(1) Average Particle Size At least 100 inactive particles in the film were observed using an SEM to determine the maximum and minimum diameters, respectively, and the arithmetic mean thereof was taken as the average particle size of the inert particles.
[0027]
(2) Surface roughness Ra
Using a surface roughness measuring instrument (SE-3F) manufactured by Kosaka Laboratory Co., Ltd., it was measured according to JIS-B-0601-1982. The measurement length was 2.5 mm.
[0028]
(3) Aluminum having a thickness of 60 nm is vapor-deposited on the surface of the reflectivity film, and the vapor-deposited surface is used as a reflection surface. MPC-3100 (Shimadzu Corporation) has a measurement light incident (reflection) angle of 5 ° and a wavelength of 400 nm to 700 nm. Was measured, and the average value was taken as the reflectance%.
[0029]
(4) Thermal Adhesion Using a laminating apparatus having two upper and lower heating rolls, the polyester film obtained in each example was pressure-laminated on one surface of a 0.2 mm thick TFS plate to produce a laminated metal plate. . The pressure was 0.3 MPa, the temperature of the heating roll was 170 ° C., and the laminating speed was 1 m / min. Then, heat treatment was performed in an oven at 150 ° C. for 2 minutes. Next, eleven vertical and horizontal cuts were made at intervals of 5 mm in the laminated film with a razor to make 100 squares. Then, an adhesive tape peeling test (using Cellotape (registered trademark)) was performed, and evaluated according to the following criteria.
○: 5% or less of peeled squares Δ: More than 5% of peeled squares and less than 10% ×: Does not thermally adhere to the metal plate, or 10% or more of peeled squares
(5) Particle Size Distribution Width The particle size distribution width of the inert particles in the polyester layer was measured using MICROTRAC HRA (manufactured by Honeywell. Inc.). Then, a cumulative curve is obtained with the total volume of the inert particles being 100% by volume, and the particle sizes of the inert particles at the points of 25% by volume and 75% by volume from the larger particle size of the cumulative curve are d25 and d75, respectively. The ratio of these d25 and d75 (d25 / d75) was defined as the particle size distribution width.
[0031]
(6) Heat shrinkage film Five samples each having a width of 2 cm and a length of 100 cm were cut out in the machine direction (MD) and the transverse direction (TD), and heat-treated in an atmosphere of 150 ° C. for 5 minutes in an untensioned state. The length of the sample was measured, and the thermal shrinkage (SMD) in the longitudinal direction of the film and the thermal shrinkage (STD) in the transverse direction were calculated by the following formulas, and measured for each of the five samples. The average value was defined as the heat shrinkage of the film.
Heat shrinkage (%) = (I0−I1) / I0 × 100
(In the above formula, I0 means the sample length (mm) before the heat treatment, and I1 means the sample length (mm) after the heat treatment. However, I0 <I1 (that is, when the film expands) is minus. expressed)
[0032]
(7) Winding workability When a polyester film was produced, the film was once wound on a master roll, then slit into a predetermined width and wound up, and then classified into the following three ranks.
：: No wrinkling was observed on the winding roll, and the end faces were uniform. △: Wrinkles were slightly observed on the winding roll, but the end faces were uniform. X: Many wrinkles were observed on the winding roll, and the end faces were also irregular. The ranks ○ and △ are levels at which there is no problem in winding workability when producing a polyester film.
[0033]
(Adjustment of raw materials)
・ Polyester A
Polyethylene terephthalate having an intrinsic viscosity of 0.65 and a melting point of 253 ° C., which is synthesized by ordinary polycondensation.
[0034]
・ Polyester B
It is a polyethylene terephthalate copolymer resin having an intrinsic viscosity of 0.70 and a melting point of 190 ° C. containing 22 mol of an isophthalic acid component produced by ordinary polycondensation.
[0035]
・ Polyester C
Polyethylene terephthalate copolymerized polyester containing 33 mol% of cyclohexanedimethanol.
[0036]
・ Polyester D
It is a polyethylene terephthalate resin having an intrinsic viscosity of 0.63 and a melting point of 253 ° C., synthesized by ordinary polycondensation and containing 0.6% by weight of amorphous silica having an average particle size of 2.5 μm.
[0037]
・ Polyester E
Monodispersion with an intrinsic viscosity of 0.64 synthesized by ordinary polycondensation and an average particle size of 1.2 μm synthesized by emulsion polymerization on a polyethylene terephthalate resin having a melting point of 253 ° C. and a particle size distribution width (d25 / d75) of 1.3. The mixture contains 1.0% by weight of kneaded crosslinked polymer particles.
[0038]
Example 1
The polyester raw material mixture of layer A shown in Table 1 below was supplied to a twin-screw extruder with vents (sub), and the polyester raw material mixture of layer B was supplied to a twin-screw extruder with vents (main) and melted at a melting temperature of 275 ° C. Then, the molten polymer from the sub-extruder and the molten polymer from the main extruder were separated by a feed block, and were taken through a die to a casting drum to obtain an unstretched film. At the time of casting, an electrostatic contact method was adopted. The thus-obtained two-layer, two-layer laminated unstretched film was fed to a longitudinal stretching roll, stretched 3.7 times at a film temperature of 83 ° C. (with an IR heater), and then guided to a tenter for 4 times in a transverse direction at 95 ° C. The film was stretched 0 times to obtain a biaxially oriented film. Next, the obtained biaxially oriented film was guided to a heat setting zone, and heat set at 180 ° C. for 5 seconds while relaxing 3% in the width direction. In addition, the thickness of the layer A and the layer B was controlled by adjusting the discharge amount of the gear pump of the sub-extruder or the main extruder.
[0039]
Example 2
A film was obtained under the same conditions as in Example 1 except that the film temperature for longitudinal stretching was 85 ° C, the transverse stretching temperature in a tenter was 100 ° C, and the heat setting temperature was 235 ° C.
[0040]
Example 3
The raw materials for the layers A and B were supplied to the sub-extruders 1 and 2, respectively, and the raw materials for the layer C were supplied to the main extruder using the polyester A. After that, the film was separated by a feed block and taken through a die to a casting drum to obtain an unstretched film having an A / C / B layer structure. Other conditions were the same as those of Example 2.
[0041]
Comparative Examples 1 to 3
The raw materials and the layer configuration were as shown in Table 2, and the other conditions were the same as in Example 2.
[0042]
Comparative Example 4
An attempt was made to form a film under the conditions of Example 1, but sticking to a roll occurred in the longitudinal stretching step, and the film could not be formed.
[0043]
[Table 1]

[0044]
[Table 2]

[0045]
In Examples 1 to 3, the reflectance on the reflecting surface on which the film was deposited was large, and the heat bonding property was excellent and the winding workability was excellent. Particularly, in Examples 2 and 3, the heat shrinkage at 150 ° C. was also small. On the other hand, Comparative Example 1 did not heat-bond because it was a single-layer film without a heat-bonding layer. In Comparative Example 2, the workability of winding the film was poor because the sum of the surface roughnesses Ra1 and Ra2 was less than 0.015 μm. In Comparative Example 3, since the surface roughness Ra1 of the layer A exceeded 0.05 μm, the reflectance was reduced.
[0046]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it can heat-adhere to a support body without using the adhesive agent which used the organic solvent etc. Also, an excellent laminated film for vapor deposition is provided, and the industrial value of the present invention is high.

Claims (1)

A laminated film having at least two layers of a polyester layer A constituting a surface to be vapor-deposited and a polyester layer B having a thermal adhesive property, wherein the laminated film satisfies the following formulas (1) and (2) simultaneously. Laminated film.
Ra1 ≦ 0.05 (1)
Ra1 + Ra2 ≧ 0.015 (2)
(In the above formula, Ra1 means the surface roughness (μm) of the layer A, and Ra2 means the surface roughness (μm) of the layer B.)