JPH0732565A - Easily adhesive laminated polyester film - Google Patents

Abstract

PURPOSE:To provide a polyester film which has an excellent adhesion and is useful for a magnetic recording medium and packaging material, etc. CONSTITUTION:An easily adhesive laminated polyester film consists of a polyester layer (A), 70mol% or higher of a dicarboxylic acid component of which is terephthalic acid and/or naphthalene decarboxylic acid, and which has a second-order transition point (TgA) of 20-150 deg.C, and a polyester layer (B), which has a heat of crystalline fusion of less than 5cal/g, and a second-order transition point (TgB) to satisfy the following equation. The easily adhesive laminated polyester film is constituted by laminating the layer (B) at least on one surface of the layer (A) by a co-extrusion method. (TgA-50)<=TgB<=(TgA+30), wherein TgA: the second-order transition point of the polyester (A) ( deg.C) TgB: the second- order transition point of the polyester (B) ( deg.C).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily-adhesive laminated polyester film, more specifically, an easily-adhesive laminated polyester film which has excellent adhesiveness and is useful as a magnetic recording medium, packaging material, display material, graphic material, laminated material and the like. Regarding the film.

[0002]

2. Description of the Related Art Polyester films, especially films made of polyethylene terephthalate or polyethylene-2,6-naphthalene dicarboxylate, are used for magnetic tapes, flexible disks, magnetic cards, graphic materials,
Although it is used in various fields such as packaging materials, since the film is oriented and crystallized, the adhesive strength is low, and many practical restrictions are imposed.

As a method for overcoming these weak points, surface processing methods such as formation of a primer layer with a water-based or solvent-based coating agent, extrusion lamination, hot melt coating and the like are known. However, when a coating agent is used, the binder resin needs to be dissolved or dispersed in the medium, which limits the selection of the resin. In some cases, the coating layer cannot be made thick enough from the viewpoint of coatability. Further, there is a drawback that the working environment is contaminated because the medium volatilizes during coating. From these points, it was difficult to design the surface to sufficiently enhance the adhesiveness of the film.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an easily-adhesive laminated polyester which does not have such drawbacks and has excellent adhesiveness and which is useful for magnetic recording media, packaging materials, display materials, graphic materials, laminated materials and the like. To provide a film.

[0005]

The present invention has the following constitution in order to achieve such an object.

70% by mole or more of the (A) dicarboxylic acid component consists of terephthalic acid and / or naphthalenedicarboxylic acid, and a polyester layer having a second-order transition point (Tg _A ) of 20 to 150 ° C. and (B) 5 cal / A layer of polyester having a heat of crystal fusion of less than g and a second-order transition point (Tg _B ) satisfying the following formula, wherein the layer (B) is laminated on at least one side of the layer (A) by a coextrusion method. Easy-adhesive laminated polyester film with a composition.

[0007]

[Equation 2] (Tg _A −50) ≦ Tg _B ≦ (Tg _A +30) [where, Tg _A : second-order transition point (° C.) of polyester (A) Tg _B : second-order transition point of polyester (B) ( ℃)]

In the present invention, since a layer of low crystallinity polyester is used as at least one surface layer of the laminated polyester film, it is possible to form a surface exhibiting a high adhesive force with respect to magnetic paints, inks and the like. Moreover, since the thickness of the surface layer can be freely increased, the adhesive force to ink, magnetic paint, etc. can be further improved. Moreover, since the layers are laminated by the co-extrusion method, the adhesive force between the layers of each layer film is extremely high. By making the second-order transition point of the second layer specific to that of the first layer, it is possible to improve the film-forming property and balance the adhesiveness.

In the present invention, the polyester (A) forming the layer (A) of the laminated polyester film is a crystalline polymer, and 70 mol% or more of the dicarboxylic acid component consists of terephthalic acid and / or naphthalenedicarboxylic acid, and It has a second-order transition point (Tg _A ) of 20 to 150 ° C.

Examples of the dicarboxylic acid component other than the terephthalic acid and / or naphthalene dicarboxylic acid component include isophthalic acid, phthalic acid, adipic acid, sebacic acid and the like.

The dihydroxy compound component constituting the polyester is ethylene glycol, 1,
4-butanediol, 1,3-propanediol, 1,
Examples thereof include 6-hexanediol, neopentyl glycol, diethylene glycol, 1,6-cyclohexanedimethanol, p-xylylene glycol and polyethylene glycol.

In the present invention, the polyester (A) forming the layer (A) needs to have a second-order transition point (Tg _A ) of 20 to 150 ° C. as described above, but this second-order transition point is 20. If the temperature is lower than 0 ° C, the film tends to cause blocking, whereas if the temperature is higher than 150 ° C, the adhesiveness is deteriorated, which is not preferable.

The layer (A) in the present invention has a heat of crystal fusion of 5
It is preferably cal / g or more. If the heat of fusion of crystals is less than 5 cal / g, the strength of the film is insufficient and the heat shrinkability becomes large, which is not preferable.

In the present invention, the polyester (B) forming the layer (B) of the laminated polyester film is a hardly crystalline or non-crystalline polymer, for example, terephthalic acid-isophthalic acid-ethylene glycol-neopentyl glycol-1, 4-butanediol copolyester, 2,6-naphthalenedicarboxylic acid-isophthalic acid-
Preferable examples include 1,4-butanediol-1,6-hexanediol copolymerized polyester and 4,4′-diphenyldicarboxylic acid-adipic acid-ethylene glycol-diethylene glycol copolymerized polyester.

As the acid component and the dihydroxy compound component constituting the polyester (B), the component constituting the polyester (A) can be used in addition to the acid component and the dihydroxy compound component constituting the copolymerized polyester. Also, a trivalent or higher valent acid component and a hydroxy compound component can be used in small amounts.

In the present invention, the polyester forming the layer (B)
Steal (B) has a second-order transition point (Tg _B) Form layer (A)
Secondary transition point (Tg_A) With
The relation must satisfy the following formula.

[0017]

(Tg _A −50) ≦ Tg ≦ _B (Tg _A +30) [where Tg _{A is} the second-order transition point (° C.) of polyester (A) Tg _{B is} the second-order transition point of polyester (B) ( ℃)]

When Tg _B <(Tg _A- 50), the film has poor blocking resistance and the process suitability during film formation after coextrusion is not good. On the other hand, when Tg _B > (Tg _A +30), the stretchability of the coextruded product is lowered and the surface property of the film becomes poor.

The layer (B) in the present invention has a heat of crystal fusion of 5
It must be less than cal / g. This crystal fusion heat is 5
If it is more than cal / g, the adhesive force is lowered, which is not preferable.

In the present invention, polyester (A),
The number average molecular weight of (B) is preferably 5,000 to 30,000. Layer (B) on one or both sides of layer (A)
To provide. Although the thickness of the layer (A) can be arbitrarily selected, it is 2 to 2
50 μm is preferable, and the thickness of the layer (B) is 0.1 to 1
0 μm is preferable. The layer (A) and the layer (B) are laminated by a coextrusion method, and the structure of the die can be arbitrarily selected.

The coextruded multilayer unstretched film is biaxially stretched to obtain a laminated stretched film. The biaxial stretching may be a multi-stage stretching such as two-stage, three-stage or four-stage. As the stretching conditions, those conventionally known or accumulated in the art can be used.

In making the laminated film, in the polyesters (A) and (B), inorganic particles such as silicon oxide, iron oxide, kaolin, aluminum oxide, aluminum silicate, calcium carbonate and titanium oxide, acrylic resin,
If necessary, organic particles such as polystyrene resin, silicone resin, melamine resin, carbon black, etc., antioxidants, lubricants, ultraviolet absorbers, colorants, pigments, antistatic agents, etc. may be added.

The laminated polyester film thus obtained has excellent adhesiveness and is useful for magnetic tapes, magnetic disks, magnetic cards, printing materials, graphic materials, photosensitive materials, packaging materials and the like.

[0024]

EXAMPLES The present invention will be further described below with reference to examples. In addition, the part in an Example means a weight part. Moreover, each characteristic value is measured by the following methods.

1) Adhesion property The following coating composition for evaluation was applied to the surface (B) of the polyester film of the sample with a Meyer bar so that the thickness after drying was about 4 μm, and dried at 100 ° C. for 3 minutes. After this 60
Aged at ℃ for 24 hours, then Scotch tape N
o. 600 (3M) width 12.7mm, length 15cm
Adhere so that air bubbles do not enter, and then use JIS C2
701 (1975), using a manual load roll to level the film and bring it into close contact, and cut into a tape width. The strength when peeled at 180 ° is measured.

[Evaluation paint] Urethane resin Nipporan 2304 (manufactured by Nippon Polyurethane) 25 parts, vinyl chloride / vinyl acetate resin S-REC A (manufactured by Sekisui Chemical Co., Ltd.) 50 parts Dispersant Resion P (manufactured by Riken Vitamin) 1 part Magnetic Agent CTX-860 (manufactured by Toda Kagaku Co., Ltd.) (500 parts) is dissolved in a mixed solvent of methyl ethyl ketone / toluene / cyclohexanone to give a 40% solution, which is dispersed for 2 hours by a sand grinder. After that, 25 parts (corresponding to solid content) of the cross-linking agent Coronate L is added and well stirred to obtain a magnetic coating material.

2) Second-order transition point of polymer Measured at a temperature rising rate of 20 ° C./min using DSC.

3) Heat of fusion of crystals Using a scanning calorimeter, a sample of polyester 0.001
The temperature of g is raised at a rate of 12 ° C. per minute (in N ₂ atmosphere), the endothermic energy due to melting is determined from the endothermic curve, and converted to 1 g of the sample weight.

[0029]

Example 1 Terephthalic acid-2,6-naphthalenedicarboxylic acid-ethylene glycol copolymerized polyester (A-) having an intrinsic viscosity [η] of 0.63 and a second-order transition point of 76 ° C.
1) and terephthalic acid isophthalic acid-ethylene glycol-neopentyl glycol copolymerized polyester (secondary transition point: 53 ° C., heat of crystal fusion: 1.2 cal / g) (B-
1) is co-extruded from a two-layer die, and is longitudinally stretched 3.6 times,
The film was stretched in the transverse direction by 3.4 times and then heat-treated at 210 ° C. to obtain a laminated film. The first layer (A) of this stretched film had a thickness of 9 μm, and the second layer (B) had a thickness of 0.7 μm.
The properties of this laminated film are shown in Table 1.

[0030]

Comparative Example 1 Table 1 shows the properties of a stretched film obtained in the same manner as in Example 1 from the first layer (A) using (A-1).

[0031]

Example 2 Copolyester (A-1) of Example 1
Coat 2,6-naphthalene dicarboxylic acid-isophthalic acid-ethylene glycol-diethylene glycol copolyester (secondary transition point 50 ° C, heat of crystal fusion 2.3 cal / g) (B-2) with a three-layer die on both sides of the layer. It was extruded and stretched in the same manner as in Example 1 to obtain a three-layer laminated film. Layer B (1
(μm) / A layer (10 μm) / B layer (1 μm). The characteristics of this laminated film are shown in Table 1.

[0032]

[Example 3] 2,6-naphthalenedicarboxylic acid-terephthalic acid-ethylene glycol copolymerized polyester (A-2) having an intrinsic viscosity [η] of 0.65 and a secondary transition point of 80 ° C
Then, the above (B-1) polyester was coextruded from a two-layer die to obtain a laminated film in the same manner as in Example 1. The structure of the film was A layer 25 μm and B layer 1.2 μm.

The characteristics of this laminated film are shown in Table 1.

[0034]

Examples 4 to 6 Polyester (B-
Table 1 shows the characteristics of the film obtained in the same manner except that the thickness of the second layer (B) prepared in 1) was changed. Further, the surface of the B layer of these films had a high adhesive force to the UV ink.

[0035]

Examples 7 to 9 Table 1 shows the characteristics of films obtained in the same manner as in Example 2 except that the thickness of the outer second layer (B) was changed.

[0036]

[Table 1]

[0037]

According to the present invention, it is possible to provide an easily-adhesive laminated polyester film which has excellent adhesiveness and is useful for magnetic recording media, packaging materials, display materials, graphic materials, laminated materials and the like.

Claims (1)

[Claims] 1. 70 mol% or less of the (A) dicarboxylic acid component
Whether the top is terephthalic acid and / or naphthalene dicarboxylic acid
The second-order transition point (Tg _A) Has
Polyester layer and (B) crystal fusion of less than 5 cal / g
Second-order transition point (Tg_B) Has
It is composed of a polyester layer, and the layer (A)
Easy-adhesive product having a structure in which the layer (B) is laminated on at least one side.
Layer polyester film. [Equation 1] (Tg_A−50) ≦ Tg_B≤ (Tg_A+30) [However, Tg_A: Secondary transition point of polyester (A)
(℃) Tg_B: Second-order transition point (° C) of polyester (B)]