JP2569905B2 - Laminated polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyester film excellent in printing suitability such as printing ink and vapor deposition suitability.

[Prior Art] Conventionally, methods for imparting printability and vapor deposition suitability to a polyester film include a method of performing corona discharge treatment and a method of mixing a low crystalline polyester and a high crystalline polyester (Japanese Patent Publication No. 64-10188). Etc.) have been proposed.

[Problems to be Solved by the Invention] However, the method of performing corona discharge treatment has insufficient adhesion, and the method of mixing a low-crystalline polyester and a high-crystalline polyester has a problem in workability. There was a problem that the adhesive strength was unstable and the uniformity of quality was poor.

The present invention provides a laminated polyester film which is excellent in processability when depositing a printing ink containing a binder selected from polyurethane, polyester and cellulose, or a metal and / or a metal oxide, has excellent print finish and vapor deposition gloss. The purpose is to do.

[Means for Solving the Problems] That is, the present invention provides an A
And a layer B composed of a low-melting polyester, wherein the surface roughness Rt / Ra [(maximum roughness) / (average roughness)] of the surface of the layer B is 12 to 100. It is about film.

The high melting point polyester referred to in the present invention is a thermoplastic polyester comprising an aromatic dicarboxylic acid and an aliphatic glycol, and specifically, polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6
Resins such as naphthalene carboxylate and their blends or copolymers. In the present invention, 90 mol% or more, more preferably 96 mol% or more of the constitution is polyethylene terephthalate, which is ethylene terephthalate, and its crystal melting energy (ΔHu) is considered from the viewpoint of durability against a heat load applied during processing. Is preferably 7 cal / g or more, more preferably 10 cal / g or more.

Next, in the present invention, the low-melting polyester is a polyester having an ester repeating unit composed of an aromatic and / or aliphatic dicarboxylic acid and an aliphatic and / or alicyclic glycol as a main skeleton, and having a lower melting point than the high-melting polyester. In particular, as an acid component, 50 to 95 mol% of an aromatic dicarboxylic acid and 5 to 50 mol of an aliphatic dicarboxylic acid
Mol%, and the glycol component is preferably composed of a component selected from aliphatic glycols. More preferably, the aromatic dicarboxylic acid is
80 to 95 mol%, aliphatic dicarboxylic acid is 5 to 20 mol%, and the melting point is preferably 210 to 245 ° C, more preferably 22 to 245 ° C.
When the temperature is 0 to 240 ° C., the adhesiveness and the workability become good.

Here, examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, and diphenic acid. As the aliphatic dicarboxylic acid,
Examples include adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicoic acid, and dimer acid. Examples of the aliphatic glycol include ethylene glycol, propylene glycol, 1,4-butanediol, and neopentyl glycol.

Among these, a particularly preferable configuration as the low-melting polyester is that the aliphatic dicarboxylic acid is composed of a dicarboxylic acid selected from adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and eicoic acid. It is preferable because it is excellent in processability and the adhesive strength is also good, and in particular, sebacic acid and dodecanedioic acid are preferable. As the aromatic dicarboxylic acid, terephthalic acid and / or isophthalic acid is preferable, and as the aliphatic glycol, ethylene glycol is preferable in view of processability. Further, the terephthalic acid component in the aromatic dicarboxylic acid is preferably at least 70 mol%, more preferably at least 80 mol%.

Further, the melting energy ΔHu of the low-melting polyester is preferably in the range of 0.1 to 6 cal / g, and more preferably in the range of 1 to 5 cal / g, from the viewpoint of adhesion to the printing ink and the vapor deposition layer.

The difference in melting point between the high-melting polyester and the low-melting polyester is preferably from 15 to 50 ° C, more preferably from 20 to 40 ° C, in order to improve the adhesiveness. From a similar viewpoint, the glass transition temperature of low-melting polyester is
It is preferably 45 to 70 ° C, more preferably 50 to 70 ° C.
Preferably it is in the range of ~ 65 ° C.

The laminated polyester film of the present invention comprises an A layer made of the high-melting polyester and a B layer made of the low-melting polyester.
In the layer, the ratio (Tb / Tb) between the thickness (Tb) of the layer B and the average particle size (D) was used.
D) from 4 to 100, preferably from 10 to 40 inert particles from 0.01 to
The content of 0.5% by weight is preferable in terms of improving the slipperiness and gloss, and more preferably 0.05 to 0.3% by weight.

Examples of the inert particles include inorganic particles such as silicon dioxide, alumina particles, calcium carbonate particles, barium sulfate particles, and silicon carbide, and particles such as crosslinked polystyrene particles and silicone particles.

Further, in the present invention, the roughness shape index Rt / R of the B layer surface
a [(maximum roughness) / (average roughness)] needs to be 12 to 100, and more preferably 15 to 40. If the roughness shape index is too small, there is a problem in adhesion. On the other hand, if it is too large, a problem arises in workability.

Further, the thickness of the B layer is 0.05 to 0.5 μm,
It is preferable in terms of improving the adhesiveness, and more preferably, it is 0.1.
07 to 0.4 μm.

Further, in the present invention, the layer A is preferably stretched and oriented uniaxially in terms of heat resistance and mechanical properties, and more preferably biaxially stretched.

Further, as the constitution of the laminated film of the present invention, A layer / B layer,
Examples are B layer / A layer / B layer, B layer / A layer / C layer, and the like. Where C
Specific examples of the layer include an antistatic layer, a mat layer, a hard coat layer, a slippery coat layer, an adhesive layer, an adhesive layer, and the like.

Further, the A layer and / or the B layer may contain a known antioxidant, heat stabilizer, antistatic agent,
A weather resistance, a flame retardant, a UV absorber, a lubricant, a crystal nucleating agent and the like may be added. Here, a hindered phenol-based additive is exemplified as an antioxidant, and a metal salt of an alkyl benzene sulfonic acid, a metal salt of an alkyl sulfonic acid, or the like is exemplified as an antistatic agent.

Next, a method for producing the film of the present invention will be described, but the present invention is not limited thereto.

Inert particles required for the high-melting polyester and the low-melting polyester are added, melt-extruded using separate extruders, and laminated in a die manifold section or a polymer tube entering the die.

As described above, the laminated body basically composed of the laminated high-melting polyester and low-melting polyester is melt-extruded into a sheet or a cylinder, and rapidly cooled to a temperature lower than the glass transition temperature of the high-melting polyester. The cast film thus obtained is instantaneously brought into contact with high-humidity air or steam having a temperature equal to or higher than the glass transition temperature of the low-melting polyester, whereby the high-melting polyester is not crystallized, but the low-melting polyester is partially crystallized.

Next, the film is stretched at least uniaxially at a temperature equal to or higher than the glass transition temperature of the high-melting polyester to obtain a stretched film. The stretching ratio is preferably in the range of 2 to 5 times in the uniaxial direction.
In the case of axial stretching, it is preferable that the area ratio is in the range of 4 to 20 times because both mechanical properties and flatness are improved.

Next, the heat treatment of the stretched film is performed by the melting point (Tm) of the layer B resin.
b) After a heat treatment in the range of −10 ° C. to Tmb + 40 ° C. for about 2 to 30 seconds, the polyester B layer is cooled at a temperature lower than the cold crystallization temperature (Tcc).

The film obtained as above can be used as needed.
A surface treatment such as a corona discharge treatment, a low-temperature plasma treatment, and a flame treatment, and the above-described coating treatment are performed.

[Effects and Uses of the Invention] The polyester film of the present invention has the following effects and uses.

(1) Not only the print processing suitability is beautiful, but also the adhesion to ink is excellent.

(2) It has excellent suitability for vapor deposition and high gloss.

In particular, the laminated film of the present invention is used for printing in which a printing ink containing a binder selected from polyurethane, polyester and cellulose is applied to the surface of the B layer, and is used by applying metal and / or metal oxide deposition to the surface of the B layer. It is preferably used as an application. here,
Examples of the metal and / or metal oxide to be deposited include aluminum, zinc, copper, iron, cobalt, nickel, silver and oxides thereof. The film thickness is 10
A range of up to 1000 ° is preferably used.

[Method for Evaluating Characteristics and Method for Evaluating Effects] Evaluation and measurement of effects used in the present invention will be summarized below.

(1) Melting energy (△ Hu), melting point (Tm), glass transition temperature (Tg) Determined using a differential scanning calorimeter DSC2 (Perkin Elmer).

The measurement was performed at 280 ° C x 5 using a 10 mg sample under a nitrogen stream.
After being melted and held for a minute, the mixture was rapidly cooled using liquid nitrogen.

When the sample thus obtained was heated at a rate of 10 ° C./min, the specific heat change based on the transition from the glassy state to the rubbery state was read, and this temperature was referred to as the glass transition temperature (Tg). did. The endothermic peak temperature based on the crystal melting was defined as the melting point (Tm), and the melting energy (△ Hu) was determined from the peak area. The correction was performed using the melting energy of indium.

(2) Surface roughness shape index According to JIS B-0601, the center line surface roughness of the sample was measured with a stylus type surface roughness meter (ET-10, manufactured by Koita Seisakusho), and the average surface roughness ( Ra). In addition, the distance between the largest peak and the deepest valley of the roughness curve is defined as the maximum surface roughness (Rt) (Reference: Jiro Nara, "Method of Measuring and Evaluating Surface Roughness" (General Technology Center, 1983) ). At this time, Rt / Ra is defined as a surface roughness shape index.

However, the stylus tip radius is 0.5 μmφ, stylus load is 5 mg, cutoff is 0.08 mm, and the measurement length is 4 mm.

The measurement was performed at 10 different points, and the average value was used as the measured value.

(3) Average particle size of particles The polyester portion is removed from the sample by a plasma low-temperature incineration method (for example, PR-503 manufactured by Daiwa Chemical Co., Ltd.) to expose the particles. The processing conditions are selected such that the polyester is ashed but the particles are not damaged. This is observed with an SEM, and the image of the particles is processed with an image analyzer (for example, QTM900 manufactured by Cambridge Instruments). For 1000 or more observed particles, the number average diameter D obtained by the following formula is calculated. Diameter.

D = ΣDi / N Here, Di is the equivalent circle diameter of the particle, and N is the number.

(4) Content of Particles The polyester is dissolved, the sample is dissolved using a solvent that does not dissolve the particles (for example, O-chlorophenol or the like), the particles are centrifuged from the solution, and the particle weight based on the total weight of the sample is determined. The weight ratio (% by weight) is defined as the particle content.

(5) Thickness of B layer The following two methods are used according to the thickness of the B layer.

(I) Method (B layer thickness is less than 0.2 μm) microscopic ellipsometry
(Mizojiri Optical Co., Ltd.).

(II) Method (B layer thickness is 0.2 μm or more) The thickness (T1) of the sample is measured with an electronic micrometer. Next, using a solvent that dissolves the layer B but does not dissolve the layer A, the layer B in the measurement section is removed, and the thickness (T2) of the same portion is measured again.

 From this result, the thickness of the layer B = T1−T2.

In each case, 20 points were measured at different locations, and the average value of 16 points obtained by omitting two points from the largest value and two points from the smallest value was taken as the thickness of the layer B.

(6) Intrinsic viscosity (IV) Measured at 25 ° C. using O-chlorophenol as a solvent. The unit is dl / g.

(7) Printability Toyo Ink's nitrocellulose-based ink CC on layer B surface
After printing ST with a gravure roll, it was evaluated by the following two methods.

A. Processing suitability The finish after printing was examined and judged according to the following evaluation criteria.

Good: No wrinkles, no print spots occurred. Bad: Wrinkles, print spots, ink repelling. B. Ink adhesion strength After leaving in an atmosphere of 40 ° C. and 90% relative humidity for 24 hours, a cellophane tape peeling test was performed.

 The evaluation criteria are as follows.

Grade 5: Does not peel at all.

Grade 4: Less than 10% peels off from the cellophane tape surface.

Third grade: 10 to 50% of the part is peeled off to the cellophane tape side.

Grade 2: 50% or more of the part peels off to the cellophane tape side.

Grade 1: Peel completely to the cellophane tape side.

 Practically, it can be used without any problem as long as it is a fourth class or higher.

(8) Adhesion of vapor deposition Aluminum metal is vapor-deposited on the surface of layer B using an electron beam heating vapor deposition machine to a thickness of 500 mm, and then an unstretched polypropylene film [CPP] using a polyester adhesive.
(Toray Synthetic Film Co., Ltd. T3501, 50 μm) laminated and left in an atmosphere of 40 ° C. and 90% relative humidity for 120 hours.
The peeled state at the time of peeling was determined by a 90 ° peeling method, and the following ranking was performed. In addition, the method of dripping water (Wet) and the method of not dripping (Dry) on the peeling interface at the time of peeling were determined.

Rank A: The deposited metal is completely left on the polyester film side.

Rank B: 50% or more of the deposited metal remains on the polyester film side.

Rank C: Less than 50% of the deposited metal remains on the polyester film side.

Rank D: The deposited metal is completely peeled off.

In practice, in the case of the dry peeling method, a problem occurs if the rank is not A, but in the case of the wet peeling method, if the rank is B or more, it can be used without any problem.

(9) Glossiness of vapor deposition surface It conforms to JIS-Z8741 (60 ゜ -60 ゜). The measurement was performed on the vapor deposition surface of the vapor deposition film.

[Examples] The present invention will be specifically described using examples.

Example 1 An intrinsic viscosity (IV) of 0.65 dl / g as a high melting point polyester
A layer of a resin obtained by adding 0.05% by weight of silica particles having an average particle size of 2 μm to polyethylene terephthalate (melting point: 256 ° C.), 90 mol% of terephthalic acid (TPA) and 10 mol of sebacic acid (SA) as acid components as a low melting polyester. % And a glycol component of ethylene glycol (EG) (IV = 0.62 dl / g, Tm = 235 ° C., Tg = 55 ° C.), and 0.08% by weight of silica particles having an average particle size of 3 μm were added to each other. Extrusion using an extruder, lamination in a die, layer A
/ B was formed into a sheet composed of two layers.

The sheet thus obtained was passed through a steam oven at 110 ° C, stretched 3.7 times in the longitudinal direction at 95 ° C, then led to a stenter and heated to 110 ° C and stretched 3.9 times in the width direction. 5% in width direction in heat treatment zone at ℃
After a heat treatment for 10 seconds, the film was rapidly cooled to 60 ° C. and wound up.

The film thus obtained has a total thickness of 12 μm,
The layer B was 0.2 μm and the surface roughness shape index was 20.

The results of examining printability and vapor deposition suitability are summarized in Table 1, and all were excellent.

Comparative Example 1 A film was formed and evaluated in the same manner as in Example 1 except that the heat treatment temperature was not subjected to the steam treatment. The surface roughness index was as small as 7, and as shown in Table 1, the vapor deposition gloss was inferior.

Example 2 Intrinsic viscosity (IV) of 0.65 dl / g as a high melting point polyester
A layer of a resin obtained by adding 0.04% by weight of silica particles having an average particle size of 1 μm to polyethylene terephthalate (melting point: 256 ° C.), 86 mol% of terephthalic acid (TPA), 7 mol% of isophthalic acid, and dodecane Resin consisting of 7 mol% of diacid and ethylene glycol (EG) as a glycol component (IV = 0.65 dl / g, Tm = 224)
C., Tg = 53 ° C.), 0.2% by weight of silica particles having an average particle size of 2 μm are added, melt-extruded using separate extruders, and laminated in a die to form two layers, A layer / B layer. It was formed into a sheet.

The sheet thus obtained was passed through a steam oven at 110 ° C., stretched 3.7 times in the longitudinal direction at 95 ° C., then led to a stenter, heated to 110 ° C., stretched 3.9 times in the width direction, and then stretched 230 times. 5% in width direction in heat treatment zone at ℃
After a heat treatment for 10 seconds, the film was rapidly cooled to 60 ° C. and wound up.

The film thus obtained has a total thickness of 12 μm,
The B layer had a thickness of 0.1 μm and a surface roughness shape index of 25.

The results of examining printability and vapor deposition suitability are summarized in Table 1, and all were excellent.

Comparative Example 2 A film was formed in the same manner as in Example 2, except that the heat treatment temperature was changed to 200 ° C. As shown in Table 1, both the ink adhesion and the aluminum deposition adhesion were inferior.

Claims (7)

(57) [Claims] 1. A layer A composed of a high-melting-point polyester and a layer B composed of a low-melting-point polyester, and the roughness shape index Rt / Ra [(maximum roughness) / (average roughness)] of the surface of the layer B is 12 or more. ~ 1
A laminated polyester film, wherein the number is 00. 2. The high-melting polyester is a polyester mainly composed of ethylene terephthalate, and the low-melting polyester is composed of 50 to 95 mol% of aromatic dicarboxylic acid, 5 to 50 mol% of aliphatic dicarboxylic acid and aliphatic glycol. The laminated polyester film according to claim 1, which is a polyester. 3. The method according to claim 2, wherein the aliphatic dicarboxylic acid is at least one selected from the group consisting of adipic acid, azelaic acid, sebacic acid, dodecandionic acid and eicoic acid. Laminated polyester film. 4. The method according to claim 1, wherein the difference in melting point between the high-melting polyester and the low-melting polyester is 15 to 50 ° C., and the glass transition temperature of the low-melting polyester is 45 to 70 ° C. The laminated polyester film according to any one of 3). 5. The laminated polyester film according to claim 1, wherein the thickness of the layer B is 0.05 to 0.5 μm. 6. Polyurethane, polyester,
The laminated polyester film according to any one of claims (1) to (5), which is used by applying a printing ink containing at least one binder selected from cellulose. 7. The method according to claim 1, wherein the surface of the layer B is subjected to metal and / or metal oxide deposition.
The laminated polyester film according to any one of the above.