JPH05230198A - Copolyester and polyester laminated film - Google Patents

Abstract

PURPOSE:To provide the subject copolyester containing a specified amount of residues having an alkaline metal sulfonate group and a specified amount of an alkaline metal, exhibiting a specified glass transition temperature and excellent in adhesiveness, blocking resistance, etc. CONSTITUTION:For example, terephthalic acid, an ester-forming sulfonic acid alkaline metal salt (preferably sodium 5-sulfoisophthalate, etc.) a copolymerization component (e.g. phenylindanedicarboxylic acid component) for raising the glass transition temperature and ethylene glycol are subjected to direct esterification reaction. During the esterification reaction, an alkaline metal chloride (preferably an alcohol-soluble chloride of sodium, etc.) is added, thus obtaining the objective copolyester containing 1 to 50mol residue having an alkaline metal sulfonate group and 1 to 3000ppm alkaline metal and exhibiting 80 deg.C glass transition temperature.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a copolyester and a laminated polyester film. More specifically, it relates to a water-soluble or water-dispersible copolyester which is excellent in adhesiveness, blocking resistance, etc. and is suitable for a coating agent, and an easily-adhesive polyester film obtained by laminating the copolyester, a magnetic recording material, It is suitably used for various photographic materials, packaging materials, electrical insulating materials, general industrial materials, and the like, and particularly for coating agents for base films and base films used for magnetic recording materials.

[0002]

2. Description of the Related Art Polyesters, particularly polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or poly-1,4-cyclohexanedimethylene terephthalate, and polyesters mainly containing these have excellent physical and chemical properties. It is widely used as a fiber, a film or a sheet, and a molded product thereof.

In particular, since polyester films have excellent heat resistance, chemical resistance and mechanical properties, they are used in many applications such as magnetic recording materials, various photographic materials, packaging materials, electrical insulating materials and general industrial materials. It is used.

However, since polyester itself is generally inactive and poor in adhesiveness, various coating materials such as magnetic paint, chemical mat paint, diazo photosensitive paint, gelatin composition, heat seal imparting composition, etc. are formed on the film surface.
When applying or printing ink etc., in order to improve the adhesiveness with the coating, physical treatment such as corona discharge or plasma or chemical treatment using alkali or amine chemicals is performed on the film surface. Various methods are known, such as a method of coating, and a method of coating an easily adhesive substance. However, the physical or chemical surface treatment method complicates the steps, not only increases the cost, but also fails to obtain sufficient adhesiveness. On the other hand, the method of coating the easily-adhesive substance can be carried out in the production process of the polyester film, is advantageous in terms of cost, and it is possible to select an adhesive substance which can be applied to various coatings. Further, various water-dispersed or water-soluble copolyesters have been proposed as adhesive substances from the viewpoints of handleability of polyester films and workability during film production. For example, JP-B-47-40873 and JP-A-50-121336 disclose that polyester is copolymerized with polyethylene glycol and an ester-forming sulfonic acid metal salt compound, and JP-A-50-834.
No. 97, JP-A-54-3848 and JP-A-59-215318 include copolymers of ester-forming sulfonic acid metal salt compounds and aliphatic dicarboxylic acid components.

[0005]

However, the above-mentioned prior art has the following problems. That is, the conventional water-dispersed or water-soluble copolyester is a combination of an ester-forming sulfonic acid metal salt compound and a polyethylene glycol or an aliphatic dicarboxylic acid component for the purpose of improving water dispersion or water-solubility. The water dispersion or water solubility is not sufficient, and since the polyethylene glycol or the aliphatic dicarboxylic acid component is copolymerized, the glass transition temperature of the polyester is remarkably lowered, so that the adhesiveness is exhibited, but the blocking resistance of the film is improved. There are drawbacks such as inferiority.

The object of the present invention is to solve these drawbacks, to provide a water-soluble or water-dispersible copolymerized polyester and a laminated polyester film which are excellent in adhesiveness and blocking resistance and are suitable as a coating agent for a base film. Especially.

[0007]

The above-mentioned object of the present invention comprises a residue having 1 to 50 mol% of a sulfonic acid alkali metal base, and an alkali metal of 1 to 3000 pp.
This can be achieved by a polyester film obtained by laminating a copolymerized polyester containing m and a glass transition temperature of 80 ° C. or higher and a copolymerized polyester.

The polyester in the present invention is a polyester containing an aromatic dicarboxylic acid or an alicyclic dicarboxylic acid and a diol as main components, and examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, phthalic acid and naphthalene. Aromatic dicarboxylic acids such as dicarboxylic acid, diphenyldicarboxylic acid and diphenyletherdicarboxylic acid can be mentioned, and the alicyclic dicarboxylic acid component can include 1,4-cyclohexanedicarboxylic acid. Two or more kinds of these acid components may be used in combination. Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3
-Propanediol, neopentyl glycol, 1,3
-Butanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 1,2
-Cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol,
Mention may be made of diols such as 2,2'-bis (4'-β-hydroxyethoxyphenyl) propane. These diol components may be used alone or in combination of two or more. As typical examples of polyester, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly-1,4-
Cyclohexane dimethylene terephthalate etc. are mentioned. Among them, polyethylene terephthalate is preferable. Further, the above polyester may be partially copolymerized with an aliphatic dicarboxylic acid, an oxyacid or a polyoxyalkylene glycol, or with another compound such as a trifunctional or higher polyfunctional compound or a monofunctional compound. You may.

The copolyester of the present invention is required to contain a residue having an alkali metal sulfonate base, and a component constituting the residue having an alkali metal sulfonate base is an ester-forming alkali metal sulfonate. Salt compounds, for example, alkali metal salts such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfonaphthalene-2,6-dicarboxylic acid, and ester-forming derivatives thereof Among them, 5-sulfoisophthalic acid and sodium and potassium salts of sulfoterephthalic acid are more preferably used.

The component constituting the residue having the alkali metal sulfonate is required to be 1 to 50 mol% with respect to the total dicarboxylic acid component constituting the polyester, and it is water-soluble or water-dispersible and adhesive. From the point, preferably 5
˜45 mol%, more preferably 8 to 40 mol%, and particularly preferably 9 to 35 mol%.

When the amount of the component constituting the residue having an alkali metal sulfonate is less than 1 mol% with respect to the total dicarboxylic acid component, sufficient water solubility or water dispersibility and adhesiveness cannot be obtained, which is preferable. Absent. On the other hand, when it exceeds 50 mol%, the adhesiveness reaches saturation and conversely the blocking resistance is lowered.

The glass transition temperature of the copolymerized polyester of the present invention must be 80 ° C. or higher, and from the viewpoint of blocking resistance, preferably 90 ° C. or higher, more preferably 1
The temperature is 00 ° C or higher, particularly preferably 105 ° C or higher. When the glass transition temperature of the copolyester is less than 80 ° C., the blocking resistance is not sufficient, which is not preferable. Although the higher the glass transition temperature of the copolyester is, the better the blocking resistance is, the water solubility or water dispersibility and the adhesiveness tend to be decreased, and the glass transition temperature of the copolyester is 160 ° C. or lower. Further, it is preferably 150 ° C. or lower.

The method for controlling the glass transition temperature of the copolyester in the present invention to 80 ° C. or higher is not particularly limited, but for example, a polyester containing a residue having an alkali metal sulfonate is added to a rigid component. Can be achieved by a method of copolymerizing Specifically, a phenylindane dicarboxylic acid component such as 1,1,3-
Trimethyl-3-phenylindane-4 ', 5-dicarboxylic acid component, diphenyl sulfone compound, for example 4,4
′ -Diphenylsulfone dicarboxylic acid component, bis (4 ′
Examples include -β-hydroxyethoxyphenyl) sulfone component. The amount of these components to be copolymerized is not particularly limited as long as the copolymerization polyester has a glass transition temperature of 80 ° C. or higher, and is preferably 1 to all dicarboxylic acid components or diol components. The range of 90 mol% is preferable from the viewpoint of adhesiveness, blocking resistance, water solubility or water dispersibility, more preferably 5 to 80 mol%, particularly 10 to 60 mol%.
Is preferred. Two or more of these copolymerization components for increasing the glass transition temperature may be used in combination.

The copolymerized polyester of the present invention is 1 to 300.
It is necessary to contain 0 ppm of an alkali metal, preferably 10 to 2000 ppm, more preferably 50 to 1
000 ppm, particularly preferably 70 to 500 ppm. The content of alkali metal in the copolyester is 1p
If it is less than pm, blocking resistance is not sufficient, which is not preferable. On the other hand, if the alkali metal content exceeds 3000 ppm, foreign matter is generated during the reaction of the copolyester, and the foreign matter in the copolyester becomes insoluble in the aqueous solution or dispersion, which is not preferable.

The method of incorporating an alkali metal into the copolyester of the present invention is not particularly limited,
For example, a method of adding an alkali metal compound at any stage of the production process of the copolyester is preferable. Further, these alkali metal compounds may be used as a reaction catalyst when producing the copolyester.
As the alkali metal compound, hydrides, chlorides, hydroxides of alkali metals such as lithium, sodium and potassium,
Examples thereof include acetate, carboxylate, alcoholate and glycolate. Of these, glycol-soluble alkali metal compounds are preferable, and for example, chlorides, hydroxides, acetates and carboxylates of alkali metals such as lithium, sodium and potassium are preferable.

As a specific method for producing the copolyester of the present invention, for example, a polyethylene terephthalate copolyester comprising a terephthalic acid component and an ethylene glycol component will be described. Direct esterification reaction of terephthalic acid, ester-forming alkali metal sulfonate compound (for example, 5-sodium sulfoisophthalic acid) and copolymerization component for increasing glass transition temperature with ethylene glycol, or dimethyl terephthalate, ester Forming alkali metal sulfonate compound (for example, dimethyl 5-sodium sulfoisophthalate) and a first step reaction in which a copolymerization component for increasing the glass transition temperature and ethylene glycol are transesterified, and the first step A second step of polycondensing the reaction product of step B., B. Terephthalic acid or its ester-forming derivative,
A polyester is produced by the second step in which the reaction product is subjected to a polycondensation reaction after the completion of the first step in which the ester-forming alkali metal sulfonate compound and ethylene glycol are directly esterified or transesterified. A method in which a copolymerization component for increasing the glass transition temperature is added during any time until the production is carried out, and the like can be mentioned.

In order to contain an alkali metal in the copolyester, a method of adding an alkali metal compound at any stage of the above-mentioned polyester production process is used.

At this time, conventionally known alkali metals, alkaline earth metals, manganese, cobalt, zinc, antimony, germanium, titanium compounds and the like are used as the reaction catalyst, and phosphorus compounds and the like can be used as the coloring preventing agent.

In the copolyester of the present invention, if necessary, a flame retardant, a heat stabilizer, an ultraviolet absorber, a pigment, a dye,
Organic lubricants such as fatty acid esters and waxes or antifoaming agents such as polysiloxanes may be added, and clay, mica, titanium oxide, calcium carbonate, kaolin, wet and dry process silica for the purpose of imparting lubricity. Furthermore, inorganic particles such as colloidal silica, calcium phosphate, barium sulfate, and alumina, and acrylic,
You may mix | blend the organic particle etc. which have styrene etc. as a structural component.

The copolyester of the present invention is used as a coating agent for various films for the purpose of imparting adhesiveness. In this case, the copolyester is dissolved in water and used as an aqueous solution, or as an organic solvent. After being dissolved in water, water is added to form an aqueous dispersion for use. Also,
In the aqueous solution or dispersion of the copolyester, if necessary, a flame retardant, a heat stabilizer, an ultraviolet absorber, a pigment,
Organic lubricants such as dyes, fatty acid esters and waxes, or defoaming agents such as polysiloxanes may be added, and clay, mica, titanium oxide, calcium carbonate, kaolin, wet and dry type may be added for the purpose of imparting lubricity. Method silica and colloidal silica, calcium phosphate,
Inorganic particles such as barium sulfate and alumina, as well as organic particles containing acrylic, styrene and the like as constituent components may be blended.

The method for producing the polyester film obtained by laminating the copolyester of the present invention is not particularly limited. For example, first, the polyester is dried and then melt-extruded to obtain an unstretched sheet, Biaxially stretched and heat treated to form a film. Biaxial stretching may be either longitudinal or transverse sequential stretching or biaxial simultaneous stretching, and the stretching ratio is not particularly limited, but usually 2.0 to 5.0 times both longitudinal and transverse are suitable. Alternatively, it may be stretched in the machine direction or the transverse direction and then re-stretched in the machine direction or the transverse direction.

At this time, the solution of the copolyester of the present invention is applied to at least one surface of the polyester film. As a coating method, a known coating method such as a reverse coating method, a gravure coating method, a die coating method, or a wire bar method can be used. The coating is preferably performed during the production process of the polyester film, more preferably by heating the unstretched sheet to 80 to 120 ° C.
The film is stretched 2.0 to 5.0 times in either direction to obtain a uniaxially oriented film. Then, a solution of the copolyester is applied, and while being subsequently heated to 90 to 140 ° C., stretched 2.0 to 5.0 times in a direction different from the uniaxial stretching, and further 1
A method of producing a film by introducing it into a heat treatment zone of 60 to 240 ° C. and heat treating it for 1 to 20 seconds is preferable.

The laminated thickness of the copolyester to be laminated on the polyester film of the present invention is not particularly limited, but is preferably in the range of 0.001 to 2.0 μ, preferably 0.01 to 1.0 μ, Preferably 0.05-
0.5μ is good. If the laminated thickness is less than 0.001 μm, sufficient adhesiveness cannot be obtained. On the other hand, the laminated thickness is 2.0μ
If it exceeds, adhesiveness is good, but blocking resistance is extremely deteriorated. The laminated thickness can be measured by various methods. For example, when the cross section of the laminated film is measured with an electron microscope or when it can be removed with a solvent or the like, it can be obtained from the difference in thickness between the removed portion and the unremoved portion. You can

[0024]

EXAMPLES The present invention will now be described in more detail with reference to examples. The properties in the examples were measured as follows.

A. Intrinsic viscosity of copolyester;
[Η] It was measured at 25 ° C. using an o-chlorophenol solvent.

B. Glass transition temperature (Tg) of copolyester Differential scanning calorimeter (DS manufactured by PERKIN ELMER)
C-2) was used, and the temperature was increased by measuring 10 mg of copolymerized polyester at a heating rate of 16 ° C./min.

C. Solubility of Copolymerized Polyester 5 g of copolymerized polyester was put into 100 g of water,
The mixture is stirred and dissolved at 2 ° C. for 2 hours, cooled, and filtered with a 5 μ filter. The water solubility of the copolyester was determined based on the dissolved state and the amount of the filtered substance. ○: The aqueous solution is transparent or slightly cloudy,
Almost no filter residue was observed. Δ: The aqueous solution was slightly cloudy, and a substance filtered off was observed. X: It was difficult to dissolve in water, or the aqueous solution was strongly clouded, and a large amount of filtered substances was observed.

D. Adhesive 100 parts by weight of Daifera Coat VD1654 (manufactured by Dainichiseika Kogyo Co., Ltd.) and Sumijour N75 {manufactured by Sumitomo Bayer Co., Ltd.} 1 part by weight on the film surface coated with an aqueous solution of copolyester and having an adhesive layer After being dried, the coating composition consisting of 1 part was applied by a bar coater so as to have a thickness of 6 μm and dried at 100 ° C. for 5 minutes to form a coating layer. A cellophane adhesive tape is attached to the surface of the coating layer, passed through a nip roll having a linear pressure of 50 kg / cm, and then rapidly peeled in the direction of 180 degrees. The area of the coating layer adhering to the cellophane adhesive tape at that time was determined to determine the adhesiveness. ◯: The area of the coating layer attached to the cellophane adhesive tape is 20
%, And excellent in adhesiveness. Δ: The area of the coating layer attached to the cellophane adhesive tape is 20
% To less than 40%, and the adhesiveness is slightly inferior. X: The area of the coating layer attached to the cellophane adhesive tape is 40
% Or more, and the adhesiveness is poor.

E. Blocking resistance A film obtained by applying an aqueous solution of copolyester and stacking the adhesive layer surfaces of the film provided with the adhesive layer (overlapping area: 3 cm x 4 cm) with a load of 500 g / 12 cm ² at 50 ° C, 85 After standing in% RH for 24 hours, the shear stress of the overlapped portion was measured using a Tensilon tensile tester.
The tensile speed was 20 cm / min.

Example 1 56.8 parts by weight of dimethyl terephthalate, 15.3 parts by weight of dimethyl 5-sodium sulfoisophthalate, 36.3 parts by weight of ethylene glycol, 35 parts by weight of bis (4'-β-hydroxyethoxyphenyl) sulfone. And 0.05 part by weight of manganese acetate as a transesterification catalyst,
After adding 0.03 part by weight of antimony trioxide as a polycondensation reaction catalyst and 0.3 part by weight of lithium acetate as an alkali metal compound, and carrying out a transesterification reaction according to a conventional method,
0.05 parts by weight of trimethyl phosphate were added. Next, the temperature was gradually raised and the pressure was reduced, and finally a polycondensation reaction was performed at 280 ° C. and 1 mmHg or less to obtain a copolyester. o
-Intrinsic viscosity was 0.75 and glass transition temperature was 110 ° C measured at 25 ° C using chlorophenol solvent. The lithium content in the polyester was 205 ppm as determined by atomic absorption spectrometry.

5 g of the obtained copolyester was added to 10 parts of water.
It was put in 0 g, dissolved by stirring at 80 ° C. for 2 hours, cooled and then 5
The mixture was filtered through a μ filter to obtain a copolyester aqueous solution. The aqueous solution of the copolyester was almost transparent, and no filter residue was observed.

On the other hand, after polyethylene terephthalate having an intrinsic viscosity of 0.60 is sufficiently dried, it is supplied to an extruder and melted at 280 ° C., extruded in a sheet form from a T-shaped die, and cooled and solidified by a cooling drum at 30 ° C. An unstretched film was obtained. Next, the unstretched film was heated to 95 ° C. and stretched 3.4 times in the machine direction to obtain a uniaxially stretched film. Further, the aqueous solution of the copolyester obtained above was applied to one surface of this uniaxially stretched film by the gravure coating method so that the coating thickness after biaxial stretching was 0.15 μm. Subsequently, it was heated to 100 ° C., stretched 3.5 times in the transverse direction, and heat-treated at 180 ° C. to obtain a polyester film having an adhesive layer with a thickness of 50 μm. The characteristics of the obtained film are shown in Table 2. The adhesiveness and blocking resistance of the film were good.

Comparative Example 1 In the same manner as in Example 1, dimethyl terephthalate 79.
5 parts by weight, 21.4 parts by weight of dimethyl 5-sodium sulfoisophthalate, and 59.8 parts by weight of ethylene glycol were used, and bis (4′-β-hydroxyethoxyphenyl) was used.
A polyester film having a copolyester and an adhesive layer was obtained without using sulfone and lithium acetate as an alkali metal compound. The results are shown in Table 2. The obtained copolyester had an intrinsic viscosity of 0.70 and a glass transition temperature of 70 ° C. Further, although the aqueous solution of the copolyester was almost transparent and no filter residue was observed, the obtained film was inferior in blocking resistance.

Examples 2-6, Comparative Examples 2-3 As shown in Table 1, copolymerization was carried out in the same manner as in Example 1, except that the types and amounts of the dicarboxylic acid component, the diol component and the alkali metal compound were changed. A polyester film having polyester and an adhesive layer was obtained. The results are shown in Table 2. Examples 2 to 6 were within the scope of the present invention, and had good adhesiveness and blocking resistance. On the other hand, Comparative Example 2 did not use an alkali metal compound, had an alkali metal content outside the range of the present invention, and had poor blocking resistance. In addition, Comparative Example 3
Had an alkali metal content outside the range of the present invention, and the obtained copolyester had poor water solubility.

[0035]

[Table 1]

[Table 2]

[0036]

INDUSTRIAL APPLICABILITY As described above, the present invention laminates a copolyester having a specific glass transition temperature and a residue having an alkali metal sulfonate group and an alkali metal and laminating the copolyester. It is a polyester film consisting of water and is excellent in water solubility or water dispersibility, adhesion, blocking resistance, etc., and is used for magnetic recording materials, various photographic materials, packaging materials, electrical insulating materials, general industrial materials, etc., especially magnetic recording materials. It is preferably used as a coating agent for a base film and a base film.

Claims (3)

[Claims] 1. A residue containing 1 to 50 mol% of a sulfonic acid alkali metal base, and containing 1 to 30 alkali metal.
Copolymerized polyester having a glass transition temperature of 80 ° C. or higher containing 00 ppm. 2. The copolyester according to claim 1, further comprising a phenylindane dicarboxylic acid component and / or a diphenyl sulfone compound copolymerized. 3. A laminated polyester film comprising a layer comprising the copolyester according to claim 1 or 2 and a polyester film layer.