JP2000336185A - Biaxially oriented polyester film for stamping wheel base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented polyester film that has high transparency, flatness, smoothness and sliding properties sufficient to permit the production of stamping wheel with excellent gloss and workability. SOLUTION: The objective biaxially-oriented polyester film includes the first inert particles and the second inert particles and these fine particles have the following properties: (1) the first inert particles are porous silica particles formed by coagulation of the primary particles with an average primary particle size of 0.01-0.1 μm and have a void volume of 0.5-2.0 ml with an average particle size of 0.1-3.0 μm in an amount of 0.01-0.1 wt.%; (2) the second particles are spherical silica particles with an average primary particle size of 0.8-3.0 μm and have an aspect ratio (major axis/minor axis) of 1.0-1.2 in an amount of 0.005-0.1 wt.%; (3) the content of the second inert particles is less than that of the first inert particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially oriented polyester film for a stamping foil, and more particularly to a high transparency, good slipperiness and good gloss, that is, good surface flatness, particularly stamping. The present invention relates to a biaxially oriented polyester film suitable for a foil base film.

[0002]

2. Description of the Related Art Stamping foils are used to obtain an appearance having a beautiful metallic luster by thermally transferring metallic characters or patterns to various paper products, various plastics, leather, wood products or other objects. As shown in FIG. 1, the stamping foil is a laminate including (1) a base film layer, (2) a release layer, (3) a coloring layer, (4) a deposition layer, and (5) an adhesive layer. When the adhesive layer of this laminate is overlaid on the article on the side to be printed and pressed with a mold heated from the base film side, only the adhesive in the portion heated by the mold melts and adheres to the article, and the stamping foil is removed. When peeled from the article, the heated portion is peeled from the substrate and printed on the article. The printed surface is required to have good gloss from the viewpoint of decorativeness, but for that purpose, the vapor deposition layer needs to be as flat and smooth as possible. The deposited layer is formed on the colored layer on the base film, but these layers are thin, and the unevenness of the base film appears almost as it is on the surface of the deposited layer, so that the surface of the deposited layer is flattened and smoothed. Requires that the surface of the base film be flattened and smoothed.

On the other hand, when the surface of the base film is flattened and smoothed, the slipperiness of the film is reduced and the appearance of winding of the film in the processing step is remarkably deteriorated. Therefore, from the viewpoint of workability, a conventional stamping foil has been used in which a base film is roughened to a certain extent while sacrificing gloss. However, in recent years, further improvement in the gloss of the vapor-deposited layer has been demanded, and the high-speed production and widening of the film accompanying the high-speed production have made it more difficult to obtain a product having a better winding form. In order to obtain a film having a good rolled shape, it is required to have excellent slipperiness and air escape. Conventionally, as a method of improving the lubricity of a film, a method of adding inorganic particles such as silicon oxide and calcium carbonate to a polyester, or a method of depositing fine particles containing calcium, lithium, and the like in a polymerization system during polyester synthesis is known. In each case, the lubricity was improved by the formation of surface projections due to the fine particles inside during film formation.

However, the improvement of the slipperiness at the projections by the fine particles as described above improves the slipperiness as the surface of the film is roughened, but lowers the gloss. That is, the flatness, the air escape property and the slipperiness are contradictory. Is what you do. As a means to solve this problem, the addition of composite inorganic particles that coexist with large-diameter and small-diameter spherical particles has been proposed. There is a limit, and it is difficult to satisfy both gloss and slipperiness at the same time.

[0005]

SUMMARY OF THE INVENTION The present inventor has solved the above problems and made intensive studies to develop an excellent stamping foil base film. As a result, porous silica particles and large-diameter spherical silica particles were converted to a specific combination. Then, they have found that the gloss and transparency of the film can be increased, and that even if the film surface is flat, good slippage and air escape can be obtained, and the present invention has been achieved. An object of the present invention is to provide a biaxially oriented polyester film that is highly transparent, flat, smooth, and excellent in slipperiness so that a stamping foil excellent in gloss and workability can be manufactured.

[0006]

An object of the present invention is to provide a film comprising a polyester containing first inert particles and second inert particles, wherein the polyester comprises:
(1) The first inert particles have an average particle size of 0.01 to
The pore volume of the aggregated 0.1 μm primary particles is 0.5
0.01 to 0.1% by weight of porous silica particles having a mean particle size of 0.1 to 3.0 μm,
(2) The second inert particles have an average particle size of 0.8 to 3.
0.005 to 0.1% by weight of spherical silica particles having a particle diameter ratio (major axis / minor axis) of 1.0 to 1.2 μm and (3) content of second inert particles Is not more than the content of the first inert particles, which is achieved by a biaxially oriented polyester film for a stamping foil base.

In the present invention, the polyester is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. In the present invention, as the polyester, for example, those containing alkylene terephthalate and / or alkylene naphthalate as a main component are preferable. Among such polyesters, for example, polyethylene terephthalate and polyethylene-2,6-naphthalate, of course, 80% by mole or more of the total dicarboxylic acid component is terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and the total glycol component is A copolymer in which 80% or more is an ethylene glycol component is preferred. At that time, the dicarboxylic acid of not more than 20% of the total acid component can be an aromatic dicarboxylic acid such as isophthalic acid, diphenoxyethane dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, anthracene dicarboxylic acid, or Examples thereof include aliphatic dicarboxylic acids such as adipic acid and sebacic acid; and alicyclic carboxylic acids such as cyclohexane-1,4-dicarboxylic acid. 20% by mole or less of the total glycol component is trimethylene glycol,
Tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, polymethylene glycol having 2 to 10 carbon atoms such as decamethylene glycol or an alicyclic diol such as cyclohexanedimethanol can be used, and, for example, hydroquinone, resorcinol, Aromatic diols such as 2,2-bis (4-hydroxydiphenyl) propane; polyalkylene glycols (polyoxyalkylene glycols) such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol; The polyester is known per se and can be produced by a method known per se.

In the present invention, the porous silica particles dispersed and contained as the first inert particles in the polyester are aggregates of primary particles having an average particle size of 0.01 to 0.1 μm. If the particle size is less than 0.01 μm, ultrafine particles are generated by crushing at the slurry stage, and this is not preferable because coarse aggregates are generated. When the average particle size of the primary particles exceeds 0.1 μm, the porosity of the particles is lost,
As a result, the affinity with the polyester is lost, so that voids are easily generated and the transparency of the film is lost, which is not preferable. Further, the pore volume of the porous silica particles in the present invention is 0.5 to 2.0 ml / g, preferably 0.6 to 2.0 ml / g.
It needs to be 1.8 ml / g. When the pore volume is less than 0.5 ml / g, the porosity of the particles is impaired,
It is not suitable because voids are easily generated and the transparency of the film is reduced.

In the present invention, the spherical silica particles dispersed and contained in the polyester as the second inert particles have a particle diameter ratio (major axis / minor axis) of 1.0 to 1.2, which is a spherical shape close to a true sphere. When the particle size ratio is increased, the void ratio is increased, and the transparency is deteriorated.

In the above added particles, the first inert particles must have an average particle diameter (secondary particle diameter) of 0.1 to 3.0 μm, more preferably 0.5 to 2.0 μm. The second inert particles have an average particle size of 0.8 to 3.0 μm,
More preferably, it is required to be 1.0 to 2.5 μm. If the average particle size of the particles is too small, the effect of improving the slipperiness becomes insufficient, and if it is too large, the glossiness of the film is lowered due to the formation of large projections, which is not preferable. The spherical silica particles preferably have a sharp particle size distribution, and the relative standard deviation representing the steepness of the distribution is preferably 0.5 or less, more preferably 0.3 or less, and particularly preferably 0.12 or less. This relative standard deviation is represented and defined by the following equation.

[0011]

(Equation 2)

As long as the above conditions are satisfied, the spherical silica and the porous silica particles are not limited to the production method and others.

In the present invention, the addition amount of the porous silica particles as the first inert particles is 0.0
1 to 0.1% by weight, preferably 0.03 to 0.0
6% by weight. The amount of the spherical silica particles added as the second inert particle component is 0.005 to the polyester.
To 0.1% by weight, preferably 0.02 to 0.05% by weight.
The amount is within the range of% by weight and equal to or less than the first inert particles. Of these, a smaller amount than the first inert particles is preferred. The amount of the first inert particles added is 0.01
% By weight, and the amount of the second inert particles added is 0.00
If the amount is less than 5% by weight, the slipping property and the air escaping property are reduced, so that it is insufficient. The total amount of the first inert particles and the second inert particles is desirably 0.015 to 0.2% by weight, preferably 0.05 to 0.11% by weight. If the total amount is too large, the transparency is reduced, the haze is increased, and the gloss after transfer when processed into a stamping foil is unfavorably deteriorated.

The polyester film of the present invention comprises:
It can be manufactured according to the manufacturing method of a conventionally accumulated biaxially stretched film. For example, a polyester containing a predetermined amount of spherical silica particles is melt-formed into an amorphous unstretched film, and the unstretched film is stretched biaxially, heat-fixed, and, if necessary, relaxation treatment. It is manufactured by doing. At this time, since the film surface characteristics change depending on the particle size and amount of the spherical silica particles or the stretching conditions, the film surface characteristics are appropriately selected from conventional conditions. For example, the stretching temperature is the first-stage stretching temperature (for example, the longitudinal stretching temperature: T ₁ ) is (Tg-10).
From the range of (Tg + 45) ° C. (however, Tg: glass transition temperature of polyester), the second-stage stretching temperature (for example, transverse stretching temperature: T ₂ ) is in the range of (T ₁ +5) to (T ₁ +40) ° C. It is good to choose from. The stretching ratio in the uniaxial direction is 2.5 or more, particularly 3 times or more, and the area ratio is 8 or more.
It is preferable to select from a range of at least 10 times, especially at least 10 times. Furthermore, the heat setting temperature is preferably selected from the range of 180 to 250 ° C, and more preferably from the range of 200 to 240 ° C. The heat setting time may be selected from the range of 1 to 30 seconds. The thickness of the biaxially oriented polyester film is preferably 3 to 100 μm, more preferably 4 to 50 μm, and particularly preferably 8 to 25 μm.

The biaxially oriented polyester film of the present invention is characterized by having better gloss and better winding properties than the conventional one. Good gloss is due to keeping the total amount of added particles low. Although reducing the amount of added particles smoothes the film surface and deteriorates the winding property, the present invention forms large protrusions on the film surface by adding a small amount of spherical silica particles having a high protrusion generation ability. As a result, the air bleeding property is improved, and the reduction in the winding property is suppressed. Further, the use of porous silica has the feature that the number of voids is small, the scattering of light due to voids is suppressed to an extremely low level, and the transparency is excellent. The reason why the voids around the porous silica are small is that the particles have a good affinity for the polyester and that a gap is hardly formed between the particle surface and the polyester due to deformation due to stress applied during stretching.

The biaxially oriented polyester film in the present invention may be subjected to a surface treatment such as an easy-adhesion coating or a corona treatment on one or both surfaces thereof. The film is made of an antistatic agent, an ultraviolet absorber,
A third component such as a colorant may be included.

[0017]

EXAMPLES Various physical properties and properties in the present invention are measured and defined as follows.

(1) Film Thickness Using a dot-type film thickness system, the thickness was measured at any 50 locations in the film width direction and at any 50 locations in the longitudinal direction near the center of the film width, and a total of 100 locations were measured. The number average value is defined as the film thickness. However, the thickness unevenness in the width direction and the longitudinal direction of the film to be measured is +20 to -2 of the average thickness.
It is assumed that it is at 0%.

(2) Average Particle Diameter of Spherical Silica The film surface is subjected to ion etching under the following conditions using a JEOL sputtering apparatus (JPC-1000 type ion sputtering apparatus). The conditions are as follows: a sample is placed in a bell jar, the degree of vacuum is increased to about 10 ⁻³ Torr, and ion etching is performed for about 10 minutes at a voltage of 0.25 kv and a current of 12.5 mA. Further, the surface of the film is sputtered with gold by the same apparatus, and 10,000-
Observation is performed at a magnification of 30,000 times, and the major axis, minor axis, and area circle equivalent diameter of at least 100 particles are obtained using Luzex 500 manufactured by Nippon Regulator. The number average value represents the major axis, minor axis, and average particle diameter of the spherical silica particles.

(3) Average Particle Diameter of Porous Silica A film is subjected to the same treatment as in the case of spherical silica, an area circle equivalent diameter of at least 100 particles is determined, and the number average is defined as an average particle diameter.

(4) Average Particle Diameter of Primary Particles of Porous Silica The measurement method of the average particle diameter of porous silica is the same as that of the above except that the magnification of the scanning electron microscope is increased.

(5) Pore volume Measured by the nitrogen adsorption / desorption method and calculated by the BET equation.

(6) Gloss of Film Surface The following evaluation is made by visual judgment. There is a feeling of roughness × There is some feeling of roughness △ No feeling of roughness ○

(7) Film haze The film haze is measured according to the measuring method A of JIS K7105 (1981).

(8) Sliding property of the film A fixed glass plate is placed under the two superposed films, and the lower film of the superposed film is taken up by a constant speed roll (about 10 cm / min). A detector is fixed to one end of the upper film (the end opposite to the direction in which the lower film is taken out), and the tensile force (F) between the films is detected. The friction coefficient μs is calculated from F and evaluated as slipperiness in the following friction coefficient range. The thread placed on the upper film used at that time is neoprene rubber (hardness 80 °), weight (W) 1.2 kg, lower area 50 cm ²
(80 mm x 62.5 mm) is used. μs = F (g) / W (g) Coefficient of friction is less than 0.40 ○ Coefficient of friction is 0.40 to 0.60 △ Coefficient of friction is 0.60 or more ×

Examples 1-4, Comparative Examples 1-3 Using dimethyl terephthalate and ethylene glycol as raw materials, manganese acetate was used as a transesterification catalyst, antimony trioxide as a polymerization catalyst, and phosphorous acid as a stabilizer. Produced polyethylene terephthalate. At that time, the lubricant particles shown in Tables 1 and 2 were dispersed in ethylene glycol and added, so that a predetermined amount was contained in the polymer. The obtained polyethylene terephthalate is dried, melt-extruded by a conventional method to form a film, and stretched at a temperature of 90 to 120 ° C. and a longitudinal magnification of 3.6 times.
The film was biaxially stretched at a transverse magnification of 3.9 and heat-set at 220 ° C. to obtain a biaxially oriented film having a thickness of 12 μm. Table 2 shows the evaluation results.
Shown in

[0027]

[Table 1]

[0028]

[Table 2]

In the film of the comparative example, a film with good gloss is inferior in slipperiness, and a film with good slipperiness is inferior in both gloss and haze. In the films of Examples, gloss, slipperiness, and haze are achieved in a well-balanced manner.

[0030]

According to the present invention, it is possible to provide a film having good gloss and excellent slipperiness, and particularly suitable for a stamping foil.

[Brief description of the drawings]

FIG. 1 shows a sectional structure of a stamping wheel.

[Explanation of symbols]

 1. 1. Base film layer Release layer 3. Coloring layer 4. Deposition layer 5. Adhesive layer

Continued on the front page (72) Inventor Takashi Saigo 3-37-19 Koyama, Sagamihara-shi, Kanagawa F-term in Sagamihara Research Center, Teijin Limited 2H086 CA12 CA21 4F071 AA43 AA45 AA46 AB26 AD03 AD06 AD07 AF30 AF32 AF58 AH19 BB08 BC01 4J002 CF061 CF081 DJ016 DJ017 FA087 GF00 GT00

Claims (2)

[Claims] 1. A film comprising a polyester containing first inert particles and second inert particles,
The polyester has (1) a primary inert particle having a pore volume of 0.5 to 2.0 ml / g in which primary particles having an average particle size of 0.01 to 0.1 μm are aggregated and having an average particle size of 0.5 to 2.0 ml / g; The diameter is 0.
0.01 to 0.1 μm of porous silica particles of 1 to 3.0 μm.
% Of spherical silica particles having an average particle diameter of 0.8 to 3.0 μm and a particle diameter ratio (major axis / minor axis) of 1.0 to 1.2 as the second inert particles. 0.005 to 0.1
(3) A biaxially oriented polyester film for a stamping foil base, wherein the content of the second inert particles is not more than the content of the first inert particles. 2. The biaxially oriented polyester film for a stamping foil base according to claim 1, wherein the spherical silica particles have a relative standard deviation represented by the following formula of 0.5 or less. (Equation 1)