JP3279921B2 - Laminated polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film, and more particularly, to a laminated polyester film having excellent concealing properties and excellent adhesion to an aqueous ink image receiving layer of an ink jet printer or the like and useful for an image receiving paper.

[0002]

2. Description of the Related Art A polyester film represented by a polyethylene terephthalate film has been widely used as a base film of a film for an image receiving paper.
In recent years, with the demand for color printers, new printing methods such as an ink jet method have been developed. An image receiving paper film for such a printing method is disclosed in JP-A-64-364.
No. 79 and Japanese Patent Application Laid-Open No. 1-95091, it is necessary to form an ink image receiving layer on a film. As the ink image receiving layer, a porous material having good ink absorbability is used, but the ink image receiving layer has poor adhesion to a polyester film used as a base film.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink-receiving layer having excellent adhesiveness and concealing properties.
An object of the present invention is to provide a laminated polyester film useful for an image receiving paper for an ink jet printer or the like.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
According to the present invention, a coating film is laminated on at least one surface of the polyester film, and further, on at least one surface of the coating film.
A laminated polyester film used by providing an aqueous ink image-receiving layer thereon, wherein the coating film has (A) a ratio of a dicarboxylic acid component having a sulfonic acid group to the total carboxylic acid component of 1 to 16 mol%. Yes, and the secondary transition point is 20-90
50 to 80% by weight of a copolyester at 10 ° C, (B) 10 to 30% by weight of a polyalkylene oxide having a number average molecular weight of 600 to 2,000, and (C) an average particle size of 20 to 80 n.
a component consisting of 3 to 25% by weight of fine particles of m
This is achieved by a laminated polyester film characterized in that the surface energy of the coating film is 54 to 70 dyne / cm.

[Polyester Film] The polyester constituting the polyester film of the present invention includes, for example, an aromatic dicarboxylic acid component such as terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, and 4,4'-diphenyl dicarboxylic acid. For example, a polyester composed of a glycol component such as ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and 1,6-hexanediol is preferable,
Especially polyethylene terephthalate, polyethylene-2
6-Naphthalene dicarboxylate is preferred. Also,
Copolymerized polyester such as the above components may be used.

If necessary, organic or inorganic fine particles as a lubricant may be added to the polyester to improve the winding property when producing a film and the transportability of the film when applying an ink image receiving layer and the like. It is preferable to include them. Examples of such fine particles include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, urea resin particles, melamine resin particles, crosslinked silicone resin particles, and the like. Also, besides fine particles, colorants, antistatic agents, antioxidants, lubricants, catalysts, polyethylene, polypropylene, ethylene-propylene-polymer, other resins such as olefinic ionomers, etc., as long as the transparency is not impaired. It can be arbitrarily contained.

It is preferable to use a polyester film having a light transmittance of 20% or less and a white color (white polyester film) as the polyester film in the present invention. This white polyester film is obtained by adding a white pigment such as titanium oxide and / or
Alternatively, it can be obtained by containing 5 to 20% by weight of barium sulfate. The white polyester film preferably has a light transmittance of 20% or less from the viewpoint of the design of printed matter when used as an image receiving paper.

The polyester film of the present invention comprises:
A biaxially stretched film having a heat shrinkage of 1% or less when held at 150 ° C. for 30 minutes has good dimensional stability when a polyester film is used as an image receiving paper, and suppresses print misalignment and the like. It is preferable because it is possible. A biaxially stretched film having such a heat shrinkage is obtained by, for example, setting the film density to 1.390 g / cm ³ or more by heat setting or heat treatment at a temperature of Tg or more of polyester after biaxial stretching. be able to.

[Coating film] In the present invention, a coating film containing (A) a copolyester, (B) a polyalkylene oxide and (C) fine particles as main components is laminated on a polyester film.

The (A) copolyester used as a component for forming this coating film is a polyester in which the ratio of a dicarboxylic acid component having a sulfonic acid group to the total dicarboxylic acid components in the molecule is 1 to 16 mol%. . Such copolyesters include terephthalic acid, isophthalic acid, 2,2
Carboxylic acid components such as 6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4'-diphenyldicarboxylic acid, phenylindanedicarboxylic acid, adipic acid, sebacic acid, 5-sulfoisophthalic acid, trimellitic acid, dimethylolpropionic acid And a dicarboxylic acid component having a sulfonic acid group such as 5-Na sulfoisophthalic acid, 5-K sulfoisophthalic acid, or 5-K sulfoterephthalic acid, and ethylene glycol, diethylene glycol, neopentylene glycol, 1,4-butanediol, 1,6
Polyester composed of -hexanediol, 1,4-cyclohexanedimethanol, glycerin, trimethylolpropane, and a hydroxy compound component such as an alkylene oxide adduct of bisphenol-A, as an aqueous solution, aqueous dispersion or emulsion. used.

In the copolyester (A), the dicarboxylic acid component having a sulfonic acid group for imparting hydrophilicity is present in an amount of 1 to 16 mol% based on all carboxylic acid components in the molecule.
, But is preferably 1.5 to 14 mol%. If the content of the dicarboxylic acid component having a sulfonic acid salt group is less than 1 mol%, the hydrophilicity of the copolyester is insufficient.
If it exceeds 6 mol%, the moisture resistance of the coating film is undesirably reduced.

The (A) copolyester must have a secondary transition point (Tg) of 20 to 90 ° C. Tg is 20
If the temperature is lower than 90 ° C., the film tends to block, while
It is not preferable that the temperature be higher than 0 ° C., since the abrasion and the adhesiveness of the film decrease.

As the polyalkylene oxide (B) used as a component for forming the coating film, polyethylene oxide, polypropylene oxide, polyethylene propylene oxide and the like can be preferably mentioned.

The molecular weight of the polyalkylene oxide (B) needs to have a number average molecular weight of 600 to 2,000. If the molecular weight is less than 600, the blocking properties of the film and the moisture resistance of the coating film are reduced. On the other hand, if it exceeds 2,000, the adhesion to the ink image-receiving layer is undesirably reduced.

The fine particles (C) used as components for forming the coating film are organic or inorganic fine particles having a particle diameter of 20 to 80 nm. Such fine particles include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles,
Examples include cross-linked silicone resin particles. If the particle size of the fine particles is less than 20 nm, the film is likely to be blocked, while if it exceeds 80 nm, the shaving property is undesirably reduced.

In the present invention, (A) a copolyester,
The mixing ratio of the (B) polyalkylene oxide and the (C) fine particles is (A) the copolyester is 50 to 80% by weight,
(B) 10 to 30% by weight of a polyalkylene oxide,
(C) 3 to 35% by weight of fine particles. If the proportion of the component (A) is less than 50% by weight, the adhesion to the polyester film is insufficient, while if it exceeds 80% by weight, the adhesion to the ink image receiving layer is undesirably reduced. If the proportion of the component (B) is less than 10% by weight, the adhesion to the ink image-receiving layer will be insufficient, while if it exceeds 30% by weight, the blocking resistance will be undesirably reduced. When the proportion of the component (C) is less than 3% by weight, the film has insufficient lubricity (transportability).

The coating film of the present invention needs to have a surface energy of 54 to 70 dyne / cm, particularly preferably 60 to 65 dyne / cm. If the surface energy is less than 54 dyne / cm, the coating properties and adhesiveness of the aqueous ink image-receiving layer will be poor, and if it exceeds 70 dyne / cm, the adhesion to the polyester film as the substrate will be insufficient, It is not preferable because moisture resistance may be insufficient.

Surface energy is 54 to 70 dyne / c
m is obtained by laminating a coating film in which (A) a copolyester, (B) a polyalkylene oxide and (C) fine particles are within the scope of the present invention, for example, to a thickness of 0.02 to 1 μm. Can be.

The laminated polyester film of the present invention has a center line average roughness (Ra) of the coating film surface of 100 nm to 100 nm.
When the thickness is in the range of 250 nm, the adhesion between the coating film and the polyester film, the adhesion between the coating film and the ink image-receiving layer, the abrasion resistance of the coating film, and the blocking resistance and transportability of the laminated film are improved. preferable. Such a coating film having Ra can be obtained, for example, by using the fine particles in the above-described ratio as a coating film component.

In the present invention, other components such as a melamine resin, an antistatic agent, a coloring agent, a surfactant, and an ultraviolet absorber can be used as components for forming a coating film, in addition to the above components.

[Lamination of Coating Film] In the present invention, a coating film composed of the above components is laminated on at least one surface of a polyester film. For example, an aqueous liquid containing a component for forming a coating film is applied to a stretchable polyester film. After that, drying, stretching and, if necessary, heat treatment can be performed to laminate. The solid concentration of this aqueous liquid is usually 30
% By weight or less, more preferably 10% by weight or less.

The stretchable polyester film is an unstretched polyester film, a uniaxially stretched polyester film or a biaxially stretched polyester film.
Among them, a vertically stretched polyester film uniaxially stretched in a film extrusion direction (longitudinal direction) is particularly preferable.

When the aqueous liquid is applied to the polyester film, if it is carried out in a normal application step, that is, a step separated from the film production step of the biaxially stretched and heat-set polyester film, trash, dust and the like are easily entrained. Not preferred. From such a viewpoint, application in a clean atmosphere, that is, application in a film manufacturing process is preferable. According to this coating, the adhesion of the coating film to the polyester film is further improved.

As the coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method and the like can be used alone or in combination. The coating amount is 0.5 to ²⁰ g per 1 m ² of the running film, and 1 to ²
10 g is preferred. The aqueous liquid is preferably used as an aqueous dispersion or an emulsion.

The stretchable polyester film coated with the aqueous liquid is guided to a drying and stretching process, which can be performed under conditions conventionally accumulated in the art. As preferable conditions, for example, the drying condition is 90.
130 ° C. × 2 to 10 seconds, and the stretching temperature is 90 to 13
0 ° C., the stretching ratio is 3 to 5 times in the machine direction, 3 to 5 times in the transverse direction, and 1 to 3 times in the machine direction if necessary.
80 to 240 ° C. × 2 to 20 seconds.

The thickness of the polyester film after such treatment is preferably 50 to 150 μm, and the thickness of the coating film is preferably 0.02 to 1 μm.

[0027]

The present invention will be further described with reference to the following examples.
In addition, each characteristic value was measured by the following method.

1. Adhesiveness 70% by weight of spherical silica (average particle diameter 18μ, average pore diameter 200 angstrom, average pore volume 1.5cc / g) 70% by weight, and 30% by weight of polyvinyl alcohol (Kuraray PVA117) are mixed with the coating surface of the polyester film. The obtained aqueous slurry was applied in a dry thickness of 20 μm, and a width of 1 μm was applied thereon.
A 2.7 mm, 150 mm long scotch tape (No. 600, manufactured by 3M Co.) was adhered so as to prevent air bubbles from entering, and the top of the scotch tape was adhered by a manual load roll described in JIS C2701 (1975). Later, cut out to tape width. When the scotch tape was peeled from the sample thus prepared, the state of peeling of the ink image receiving layer from the polyester film was observed, and the adhesion was evaluated as follows. A: No peeling was observed at all and good adhesion B: Slight peeling was observed at the foreign matter portion C: Peeling was noticeably observed

2. Coefficient of friction According to ASTM D 1894-63, a static friction coefficient was measured by applying a load of 1 kg with the front and back surfaces of the film together using a slipper measuring device manufactured by Toyo Tester Co., Ltd. If the coefficient of friction exceeds 0.6, film transportability will be impaired.

3. Blocking property Two films cut to a width of 50 mm are piled up, and 50 kg /
After treatment at 40 ° C. × 50% RH × 17 hours under a load of cm ² , the peel strength (g
/ 50 mm). Evaluation was made as follows by the value of the peel strength. Peel strength ≦ 10 g / 50 mm: good blocking property 10 g / 50 mm <peel strength ≦ 30 g / 50 mm—somewhat good blocking property 30 g / 50 mm <peel strength: poor blocking property

4. Surface energy WA Zisman: “Contact Augle, Wettability and Adh
esion ", Am. Chem. Soc., (1964), the measured critical surface tension γc was used as the surface energy.

5. Secondary transition point Measured at a heating rate of 20 ° C./min with a Thermal Analyst 2000 type differential calorimeter manufactured by DuPont.

6. Intrinsic viscosity The viscosity of the solution with orthochlorophenol solvent is 35 ℃
Was measured and determined.

7. Water dispersibility The coating agent was diluted with water to form a 0.2% by weight aqueous dispersion, and the light transmittance was measured using a quartz cell with a double beam spectrophotometer (type 228A) manufactured by Hitachi, Ltd. . Evaluation was made as follows from the measurement results. Light transmittance ≧ 50% good water dispersibility 50%> light transmittance ≧ 30% slightly good water dispersibility 30%> light transmittance poor water dispersibility

8. Moisture resistance In the evaluation of the blocking property, the treatment condition was 60 ° C.
Peeling strength (g / 50 mm) was measured in the same manner except that x70% RH x 17 hours. Evaluation was made as follows from the measurement results. Peel strength ≦ 10 g / 50 mm: good moisture resistance 10 g / 50 mm <peel strength ≦ 30 g / 50 mm—somewhat good moisture resistance 30 g / 50 mm ≦ peel strength: poor moisture resistance

9. Light transmittance The light transmittance was measured using a HR-100 haze meter manufactured by Murakami Color Research Laboratory in accordance with ASTM D1003.

10. Heat Shrinkage The shrinkage after heat treatment of the polyester film at 150 ° C. for 30 minutes was measured at a distance between the gauge points of 30 cm.

11. Center line average roughness (Ra) According to JIS B0601, using a high-precision surface roughness meter SE-3FAT manufactured by Kosaka Laboratory Co., Ltd.
μm, load 30 mg, magnification 50,000 times, cutoff 0.
Under the condition of 08 mm, a portion of the measured length L is drawn from the surface roughness curve in the direction of its center line under the condition of 08 mm, and the center line of the drawn portion is set as the X axis, and the direction of the longitudinal magnification is set as the Y axis. When the roughness curve was represented by Y = f (x), the value given by the following equation was represented in nm.

[0039]

(Equation 1)

In this measurement, the reference length is 1.25 mm, and
Four samples were measured and represented by an average value.

Example 1 A composition comprising 90% by weight of a polyester (intrinsic viscosity: 0.62) comprising a terephthalic acid component and an ethylene glycol component and 10% by weight of titanium oxide was placed on a rotary cooling drum maintained at 20 ° C. After being melt-extruded into an unstretched film, and then stretched 3.6 times in the machine axis direction, the acid components are terephthalic acid [60 mol%], isophthalic acid [37 mol%] and 5-Na Sulfoisophthalic acid [3 mol%], glycol component is ethylene glycol [40 mol%], neopentyl glycol [40 mol%] and bisphenol-A
65% by weight of a copolymerized polyester (Tg = 30 ° C., hereinafter simply referred to as [E]) comprising ethylene oxide adduct [20 mol%], 16% by weight of polyethylene oxide having a molecular weight of 1000, and a crosslinked acrylic resin having an average particle size of 40 nm An aqueous liquid having a solid content of 4% by weight and having a composition of 10% by weight of particles and 9% by weight of polyoxyethylene nonylphenyl ether was applied by a roll coater. Then
The longitudinally stretched film coated with the aqueous liquid is stretched 4 times in the transverse direction while drying, and further heat-set at 230 ° C. to a thickness of 100 μm.
Was obtained. The film thickness of this film is 0.03 μm, the center line average surface roughness is 180 nm, the light transmittance is 3%, and the surface energy is 60 dyne / c.
m, the heat shrinkage was 0.9% in the vertical direction and 0.2% in the horizontal direction. Table 1 shows the characteristics of this film.

Comparative Example 1 Except that the aqueous liquid was not applied,
Table 1 shows the properties of the biaxially stretched polyester film obtained in the same manner as in Example 1.

Examples 2 to 7 Biaxially oriented polyester films were obtained in the same manner as in Example 1 except that the types and ratios of the coating agents were changed as shown in Table 1. Table 1 shows the characteristics of this film.

[0044]

[Table 1]

As is clear from the results shown in Table 1, the laminated polyester film of the present invention has excellent adhesiveness.

In Table 1, the type of copolyester E
And F (Note 1) indicate the following copolymer.

E: terephthalic acid [60 mol%] isophthalic acid [37 mol%] 5-Na sulfoisophthalic acid [3 mol%] / ethylene glycol [40 mol%] neopentyl glycol [40 mol%] Copolymer of ethylene oxide adduct of bisphenol-A [20 mol%] (Tg = 30 ° C.) F: 2,6-naphthalene dicarboxylic acid [20 mol%]
Isophthalic acid [76 mol%] 5-K sulfoterephthalic acid [4 mol%] / ethylene glycol [50 mol%]
Neopentyl glycol [50 mol%] copolymer (Tg
= 42 ° C.) In Table 1, the type P of the polyalkylene oxide
And Q (Note 2) indicate the following polymers.

P: polyethylene oxide having a molecular weight of 1,000 Q: polypropylene oxide having a molecular weight of 1200

Examples 8 to 11 and Comparative Examples 2 and 3
(A) A biaxially stretched polyester film was obtained in the same manner as in Example 1, except that the types of copolyester were changed as shown in Tables 2 and 3, except that copolyesters having different Tg were used. Table 2 shows the properties of the obtained film.

[0050]

[Table 2]

[0051]

[Table 3]

As is clear from the results shown in Table 2, the laminated polyester film of the present invention is excellent in blocking resistance and adhesiveness.

Examples 12 to 16 and Comparative Examples 4 and 5
(A) A biaxially stretched polyester film was obtained in the same manner as in Example 1, except that the proportion of the dicarboxylic acid component containing a sulfonic acid group in the copolyester was changed as shown in Table 4. Table 4 shows the properties of the obtained film.

[0054]

[Table 4]

As is evident from the results shown in Table 4, the coating composition of the present invention is excellent in water dispersibility, and the laminated polyester film of the present invention is excellent in moisture resistance.

[Examples 17 to 19 and Comparative Examples 6 and 7]
A biaxially stretched polyester film was obtained in the same manner as in Example 1, except that the ratio of (A) copolyester, (B) polyalkylene oxide and (C) fine particles was changed as shown in Table 5. Table 5 shows the properties of the obtained film.

[0057]

[Table 5]

As is clear from the results shown in Table 5, the laminated polyester film of the present invention is excellent in adhesiveness and transportability.

Examples 20 and 21 and Comparative Examples 8 and 9
A biaxially stretched polyester film was obtained in the same manner as in Example 1, except that the ratio of (A) copolyester, (B) polyalkylene oxide and (C) fine particles was changed as shown in Table 6. Table 6 shows the properties of the obtained film.

[0060]

[Table 6]

As is clear from the results shown in Table 6, the laminated polyester film of the present invention is excellent in adhesiveness and transportability.

[Examples 22 and 23 and Comparative Examples 10 and 1
1] A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the particle size of the fine particles (C) was changed as shown in Table 7. Table 7 shows the properties of the obtained film.

[0063]

[Table 7]

As is clear from the results shown in Table 7, the laminated polyester film of the present invention has excellent blocking resistance.

[Examples 24 and 25 and Comparative Examples 12 and 1
3] A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that the ratios of (A) copolyester, (B) polyalkylene oxide and (C) fine particles were changed as shown in Table 8. Table 8 shows the properties of the obtained film.

[0066]

[Table 8]

As is clear from the results shown in Table 8, the laminated polyester film of the present invention is excellent in adhesiveness and transportability.

[0068]

The laminated polyester film of the present invention is
It has excellent concealing properties and excellent adhesiveness to an aqueous ink image receiving layer of an ink jet printer or the like, and is useful as an image receiving paper.

Continuation of the front page (56) References JP-A-61-149353 (JP, A) JP-A-60-141525 (JP, A) JP-A-60-89334 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04

Claims (6)

(57) [Claims] 1. A coating film is laminated on at least one side of a polyester film, and is further coated on at least one side of the coating film.
A laminated polyester film used by providing an aqueous ink image-receiving layer on the coating film, wherein the coating film has (A) a ratio of a dicarboxylic acid component having a sulfonic acid salt group to all carboxylic acid components of 1 to 16 mol%. Yes, and the secondary transition point is 20-90 ° C
50 to 80% by weight of a copolyester, (B) 10 to 30% by weight of a polyalkylene oxide having a number average molecular weight of 600 to 2,000, and (C) an average particle diameter of 20 to 80 nm.
A laminated polyester film comprising a component consisting of 3 to 25% by weight of fine particles as a main component, and a surface energy of the coating film is 54 to 70 dyne / cm. 2. The polyester film having a light transmittance of 2
The laminated polyester film according to claim 1, which is 0% or less and is white. 3. The polyester film has a viscosity of 3 ° C. at 150 ° C.
The laminated polyester film according to claim 1, which is a biaxially stretched film having a heat shrinkage of 1% or less when held for 0 minutes. 4. The center line average roughness Ra of the coating film surface is 100.
3. The laminated polyester film according to claim 2, wherein the thickness is in the range of nm to 250 nm. 5. The polyester film having a light transmittance of 2
0% or less, and the laminated polyester film 請 Motomeko 2 wherein the white. 6. The laminated polyester film according to claim 5, which is used for an image receiving paper for an ink jet printer.