JPH0762212A - Polyester aqueous dispersion and readily bondable polyester film - Google Patents

Abstract

PURPOSE:To obtain the subject aqueous dispersion, capable of forming a readily bondable film excellent in antistatic properties and surface properties and useful as magnetic tapes, etc., by dispersing fine particles of an amorphous copolyester composed of a specific glycol component and having a specific glass transition temperature in water. CONSTITUTION:This aqueous dispersion is obtained by dispersing fine particles of an amorphous copolyester in which a part of a glycol component is a sulfo- aromatic glycol, preferably a compound, expressed by formula I {X<1> is H or a 1-5C alkyl; Y is single bond, CH2, C(CH3)2 or SO2; M<1> is one equiv. cation; Z is H or SO3M<1>; (m) and (n) are (m)not equal to 0; (n)not equal to 0; [m+n] is 2-50} or formula II [X<2> is X<1>; M<2> is M<1>; (p) and (q) are (m) and (n)] and having <55 deg.C glass transition temperature in water. Furthermore, this readily bondable polyester film can be obtained by coating a polyester film with the aqueous dispersion and forming a primer layer having 0.01-5mum thickness thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous polyester dispersion and an easily adhesive polyester film coated with the aqueous dispersion. More specifically, a polyester aqueous dispersion capable of forming a coating film (easy adhesion layer) having low charge, good surface property, and excellent adhesiveness, and a packaging material, magnetic card, magnetic tape coated with the same. , An easily-adhesive polyester film useful for magnetic disks, printing materials and the like.

[0002]

BACKGROUND OF THE INVENTION Thermoplastic polyesters such as polyethylene terephthalate or its copolymers, polyethylene naphthalene dicarboxylate or its copolymers, or blends of these with small proportions of other resins are melt extruded and biaxially stretched. Then, the polyester film obtained by heat fixing is excellent in mechanical strength, heat resistance, chemical resistance and the like, and is used in various industrial fields. However, since its surface is highly oriented, it has a drawback that it is poor in accepting ink, magnetic paint and the like.

As a method of increasing the receptivity of the surface of the polyester film, there is a method of previously forming a primer layer (easy adhesion undercoat layer) of a synthetic resin on the surface of the film to form a thin surface primer layer different from the base film. The primer layer is formed by applying a solution of a synthetic resin in an organic solvent or an aqueous solution (aqueous solution, water dispersion) to the surface of the film.

As a resin aqueous solution for forming the primer layer, an aqueous solution of a polyester polymer, an aqueous solution of an acrylic polymer and the like are known. Among them, the aqueous liquid of polyester polymer is Japanese Patent Publication No. 56-5476.
JP-A No. 60-248232 and JP-A No. 60-248232. However, a film coated with a primer layer formed from an aqueous liquid of a polyester-based polymer disclosed in Examples of the prior art has a large charging property, and an electric charge is accumulated at the time of rewinding, so that the accumulated electric charge is discharged. There is a risk that an explosive fire may occur, and further, there is a drawback that dust and the like are adsorbed by the accumulated electric charge, which causes dropout in magnetic applications, for example.
When using an aqueous dispersion of polymer particles,
If the polymer fine particles maintain a particulate shape in the product film, there is a drawback that the film surface is roughened.

[0005]

DISCLOSURE OF THE INVENTION The present inventor has conducted earnest research to solve the drawbacks of the prior art and to develop a material for a primer layer having a small chargeability, a smooth surface and an excellent adhesive property. As a result, the chargeability of the primer layer formed from the conventional polyester-based polymer aqueous solution was copolymerized in order to impart hydrophilicity to the polyester-based polymer.
It was clarified that it was caused by an aromatic dicarboxylic acid component containing a sulfonic acid metal salt such as sodium sulfoisophthalic acid,
Based on these findings, the present invention arrived at the polyester water dispersion of the present invention, which provides an easily-adhesive primer layer with less charge and good surface property.

Therefore, an object of the present invention is to reduce the charge,
An object of the present invention is to provide a polyester water dispersion capable of forming a coating film (primer layer: easy adhesion layer) having excellent surface smoothness and easy adhesion, and an easy adhesion polyester film coated with the same.

[0007]

The object of the present invention is to:
According to the present invention, firstly, a part of the glycol component is composed of a sulfoaromatic glycol component and is composed of an aqueous dispersion of fine particles of an amorphous copolyester having a glass transition temperature of less than 55 ° C. Is achieved with a polyester water dispersion.

In the amorphous copolyester according to the present invention, a part of the glycol component is a sulfoaromatic glycol component. As the sulfoaromatic glycol component, for example, the following formula (1)

[0009]

[Chemical 1]

Here, X ¹ is a hydrogen atom or has 1 to 1 carbon atoms.
5 is an alkyl group of 5, Y is a single bond, —CH ₂ —, —C
(CH _{3) 2} - or -SO ₂ - and is, M ¹ is one equivalent of a cation, Z is a hydrogen atom or -SO ₃ M ¹ (the definition of M ¹ are as defined above), and the n m is not zero, but n +
It is a number that satisfies m = 2 to 50,

A lower alkylene oxide adduct of sulfobisphenols represented by the following formula (2)

[0012]

[Chemical 2]

Here, X ² is a hydrogen atom or a carbon number of 1 to
5 is an alkyl group, M ² is one equivalent of cation, p and q are not zero, and are numbers satisfying p + q = 2 to 50,

A preferable example is a lower alkylene oxide adduct of sulfohydroquinone represented by:

In the above formulas (1) and (2), the number of carbon atoms is 1 to
The alkyl group of 5 may be linear or branched. As one equivalent of cation, for example, an alkali metal cation, 1/2 of an alkaline earth metal cation, or a phosphonium ion can be preferably mentioned.

The proportion of the sulfoaromatic glycol component is preferably 0.1 mol% or more of the total glycol component,
More preferably, it is 0.1 to 10 mol%. If the sulfoaromatic glycol component is less than 0.1 mol%, it will be difficult to uniformly disperse the obtained polyester in water.
Even if it exceeds the mol%, no further improvement in water dispersibility is observed.

Examples of glycols other than sulfoaromatic glycols include ethylene glycol, linear aliphatic glycols, poly (alkoxy) glycols, cyclohexanedimethanol, lower alkylene oxide adducts of bisphenols, and neopentyl glycol. . These glycols can be used alone or in combination of two or more.

Examples of the dicarboxylic acid component forming the amorphous copolyester in the present invention include aliphatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, phenylindane dicarboxylic acid and adipic acid. . These dicarboxylic acid components may be used alone or in combination of two or more.

The glass transition temperature of the amorphous copolyester is less than 55 ° C. When the glass transition temperature of the amorphous copolyester is less than 55 ° C., polymer fine particles are fused to each other in the drying step after coating the film with the aqueous dispersion, and the surface smoothness is improved.

The amorphous copolyester referred to in the present invention is a polyester which shows no or almost no melting point peak when measured with a differential thermal analyzer Du Pont DSC2100 at a heating rate of 20 ° C./min. . When the polyester has a melting point peak, the solubility of the polymer in a hydrophilic organic solvent is remarkably deteriorated and water dispersion becomes impossible, which is not preferable.

As the copolymer having a glass transition temperature of less than 55 ° C., preferably a straight chain aliphatic dicarboxylic acid, a straight chain aliphatic glycol, a polyalkoxy glycol or a polyalkylene glycol of bisphenol A is added in an amount of 4 mol or more of lower alkylene oxide. Preferable examples include copolymerization of the body and the like and combinations thereof. Further, a copolymer using a combination of several kinds of dicarboxylic acids and glycols is also preferable. It is also possible to copolymerize a small amount of an aromatic dicarboxylic acid having a sulfonic acid group such as 5-sodium sulfoisophthalic acid as long as the chargeability is not impaired.

The polyester water dispersion of the present invention, particularly the polyester water dispersion for coating a polyester film, can be produced, for example, by the following method.

The amorphous copolyester is first treated at 20 ° C.
At a solubility of 20 g or more in 1 liter of water and a boiling point of 100 ° C. or lower, or at 100 ° C. or lower, it is dissolved in a hydrophilic organic solvent that is azeotropic with water. As this organic solvent,
Examples thereof include dioxane, acetone, tetrahydrofuran, methyl ethyl ketone and the like. It is also possible to add a small amount of surfactant to such a solution.

Next, water is added to the organic solvent in which the amorphous copolyester is dissolved, with stirring, preferably with heating and high speed stirring, to obtain a pale white to milky white dispersion. A bluish white to milky white dispersion can also be obtained by a method of adding the organic solvent to water under stirring.

The resulting dispersion is further distilled under normal pressure or reduced pressure, and the hydrophilic organic solvent is distilled off to obtain the desired polyester aqueous dispersion. When a hydrophilic organic solvent that is azeotropic with water is used as the organic solvent, water is azeotroped when the organic solvent is distilled off, so the amount of water loss (azeotrope) should be taken into consideration. It is desirable to disperse in

The polyester aqueous dispersion of the present invention preferably has a solid content concentration of 40% by weight or less. When the solid content concentration exceeds 40% by weight, re-aggregation of fine particles of the amorphous copolyester dispersed in water is likely to occur and the stability of the aqueous dispersion is reduced. On the other hand, there is no particular lower limit of the solid content concentration, but if the concentration is too low, the time required for drying becomes long. The average particle size of the copolyester fine particles is usually 1 μm or less, preferably 0.8 μm or less. The polyester aqueous dispersion thus obtained can be applied to one side or both sides of a polyester film described below and dried to impart easy adhesion to the film.

The polyester aqueous dispersion may be used by appropriately containing a surfactant such as an anionic surfactant or a nonionic surfactant during coating. As an effective surfactant, the surface tension of the polyester aqueous dispersion can be lowered to 40 dyne / cm or less, and the wetting of the polyester film is promoted. Many known surfactants can be used. As examples thereof, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfonate, alkyl sulfosuccinate, quaternary ammonium chloride, alkyl Examples thereof include amine hydrochloride and sodium dodecylbenzene sulfonate. Further, an antistatic agent, a filler, an ultraviolet absorber, a lubricant, a colorant and the like may be added to the polyester aqueous dispersion, if necessary.

In the present invention, a preferable example of the polyester film is a film made of polyethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate, polybutylene terephthalate, or a copolymer obtained by copolymerizing these with other copolymerization components. Can be mentioned. The polyester film may be an unstretched film, a uniaxially stretched film, or a biaxially stretched film,
A uniaxially or biaxially stretched film is suitable.

The step of applying the polyester aqueous dispersion to the polyester film can be arbitrarily selected. The polyester aqueous dispersion is applied to an unstretched film or a uniaxially stretched film, then dried by heating and then further stretched, or applied to a biaxially stretched film and dried. Of these, it is preferable to apply it to a uniaxially stretched film. The coating can be carried out by a conventional method, and for example, kiss coat, reverse coat, gravure coat, die coat and the like are used. The coating amount is 0.01
To 5 μm (dry), more preferably 0.0
1-2 μm (dry), most preferably 0.01-3 μm
m (dry).

Thus, according to the present invention, at least one layer has a layer composed of an amorphous copolyester having a sulfoaromatic glycol component as a part of the glycol component and a glass transition temperature of less than 55 ° C. An easily-adhesive polyester film characterized by the above is also provided.

The easily-adhesive polyester film of the present invention has a high adhesive force, a low electrostatic charge and an excellent surface property, and therefore, for example, a magnetic card, a magnetic tape, a magnetic disk,
It is useful for printing materials, graphic materials, photosensitive materials and the like. Especially, it is especially useful for a vapor-deposited magnetic tape.

[0032]

EXAMPLES The present invention will be described in more detail with reference to examples. In addition, "part" in an Example means a weight part. (1) Glass Transition Temperature and Melting Point of Copolymerized Polyester It was measured at a temperature rising rate of 0 ° C. to 20 ° C./min using a differential thermal analyzer type 2100 manufactured by Du Pont.

(2) Adhesiveness A (primer-coated) polyester film was coated with the following magnetic paint under predetermined conditions, and Scotch tape No. 600 (manufactured by Three M) width 19.4 m
m, 8 cm in length without sticking bubbles, and leveled with a manual load roll described in JIS C2701 (1975). Adhesive layered part 5 cm was using Tensilon UM-II manufactured by Toyo Baldwin. Head speed 300
This sample was T-peeled at mm / min, the peel strength at this time was determined, and this was divided by the tape width to determine g / cm. In addition, in the T-shaped peeling, the tape side of the laminated body is faced down and the distance between the take-up chucks is set to 5 cm.

Preparation of magnetic coating material for evaluation: Nitrocellulose RS1 / 2 (Flakes containing 25% isopropanol: manufactured by Daicel Co., Ltd.) was dissolved in a paint lacquer thinner to prepare a 40% by weight solution. 9 parts, followed by 32.5 parts of polyester resin (Desmophen # 1700: manufactured by Bayer), 26.0 parts of chromium dioxide magnetic powder, soybean oil fatty acid (Reciion P: manufactured by Riken Vitamin Co., Ltd.) as a dispersant / wetting agent. , Cationic surfactants (cation A
B: Nihon Yushi Co., Ltd.) and squalene (shark liver oil) are put into a ball mill at 1 part, 0.5 part and 0.8 part, respectively. Methyl ethyl ketone / cyclohexanone / toluene = 3 /
282 parts of a mixed solution of 4/3 (weight ratio) is further mixed and sufficiently pulverized to prepare a mother liquor paint (45% by weight). To 50 parts of this mother liquor, 48 parts of an addition reaction product of trimethylolpropane and tolulane diisocyanate (Coronate L: manufactured by Nippon Polyurethane Industry Co., Ltd.) and 6.25 parts of butyl acetate were added, and finally 42.75. A magnetic paint for evaluation of weight% was obtained.

(3) Chargeability: 2 polyester films (treated with a primer coating)
Ionized air blower (model 12 manufactured by Hugle Electronics Co., Ltd.) cut into a size of 10 cm x 10 cm
After the charge was removed in 0), the amount of charge after rubbing 5 times with a chromium-plated iron roll was measured using a static electricity measuring device (Stachilon-TL manufactured by Shishido Electrostatic Co., Ltd.).

(4) Film surface property The surface of the (primer-coated) polyester film was observed with an electron microscope at a magnification of 100,000, and a film having no fine particles due to the water dispersibility of the copolymer was accepted. .

Example 1 <Production of Copolyester> Dimethyl terephthalate 1
00 parts, dimethyl isophthalate 18 parts, 3,3'-disodium sulfobisphenol A ethylene oxide 2
Molar adduct 4 parts, tetramethylene glycol 64 parts and ethylene oxide 4 mol adduct of bisphenol A 5
5 parts were charged into a transesterification reactor, and 0.07 parts of tetrabutoxytitanium was added thereto, and the temperature was controlled at 230 ° C. under a nitrogen atmosphere and heating was carried out to distill off the produced methanol to effect the transesterification reaction. went. Then, 0.6 part of Irganox 1010 (manufactured by Ciba Geigy) was added to this reaction system, and then the temperature was gradually raised to 255 ° C., and the system was subjected to a polycondensation reaction by reducing the pressure to 1 mmHg to obtain an intrinsic viscosity. An amorphous copolyester having a glass transition temperature of 0.60 and a glass transition temperature of 27 ° C. was obtained. The composition of the copolyester is shown in Table 1.

<Preparation of Polyester Aqueous Dispersion> 20 parts of this copolymerized polyester was dissolved in 80 parts of tetrahydrofuran, and 180 parts of water was added dropwise to the resulting solution under high speed stirring of 10,000 rpm to give a bluish tinge. A milky white dispersion was obtained. Next, this dispersion was distilled under a reduced pressure of 20 mmHg to remove tetrahydrofuran. Thus, a polyester aqueous dispersion having a solid content concentration of 10% by weight was obtained.

Further, 2 parts of a nonionic surfactant: polyoxyethylene nonylphenyl ether (HLB = 12.8) was added to 180 parts of the polyester aqueous dispersion, and 618 parts of water was further added to prepare a coating solution.

<Production of easily adhesive polyester film>
Polyethylene terephthalate having an intrinsic viscosity of 0.65 measured in 35 ° C. o-chlorophenol was melt extruded to obtain an unstretched film having a thickness of 158 μm, which was then stretched 3.5 times in the machine axis direction and then prepared as above The coating solution was applied to one side of the uniaxially stretched film. Then 105
The film was stretched 3.9 times in the transverse direction at ℃ and heat-treated at 200 ℃ for 4.2 seconds. The average coating amount was 20mg / m ² and the thickness was 12.2μ.
A biaxially stretched primer-coated polyester film of m was obtained. The adhesiveness and chargeability of the treated surface of this film were measured. The results are summarized in Table 1.

Examples 2 to 4 The same procedure as in Example 1 was repeated except that the copolymerization amounts of 3,3'-disodium sulfobisphenol A ethylene oxide 2 mol adduct and ethylene glycol were changed, and the results are shown in Table 1. An amorphous copolyester having a composition glass transition temperature of 28 to 31 ° C. was obtained. Next, an aqueous polyester dispersion and a coating liquid were prepared in the same manner as in Example 1 except that these copolyesters were used. Further, a biaxially stretched primer-coated polyester film was obtained in the same manner as in Example 1 except that these coating solutions were used. The adhesiveness, chargeability and surface property of the treated surface of this film were measured.
The results are summarized in Table 1.

Examples 5 to 8 The procedure of Example 1 was repeated except that the 2 mol adduct of 3,3'-disodium sulfobisphenol A ethylene oxide was changed to the 2 mol adduct of sodium sulfohydroquinone ethylene oxide. Amorphous copolyester having a glass transition temperature of 30 to 31 ° C. having a composition shown in Table 1 was obtained. Next, an aqueous polyester dispersion and a coating liquid were prepared in the same manner as in Example 1 except that these copolyesters were used. Further, a biaxially stretched primer-coated polyester film was obtained in the same manner as in Example 1 except that these coating solutions were used. The adhesiveness, chargeability and surface property of the treated surface of this film were measured. The results are summarized in Table 1.

Example 9 10 3 3'-Disodium Sulfobisphenol A Ethylene oxide 2 moles The procedure of Example 1 was repeated except that the sodium salt was changed to the lithium salt and the sulfonium salt, and the results are shown in Table 1. An amorphous copolyester having a glass transition temperature of 31 ° C. having the composition shown was obtained. Next, an aqueous polyester dispersion and a coating liquid were prepared in the same manner as in Example 1 except that these copolyesters were used. Further, a biaxially stretched primer-coated polyester film was obtained in the same manner as in Example 1 except that these coating solutions were used. The adhesiveness, chargeability and surface property of the treated surface of this film were measured. The results are summarized in Table 1.

Examples 11 to 13 An amorphous copolymer having a composition shown in Table 1 and having a glass transition temperature of 10 to 53 ° C. was prepared in the same manner as in Example 1 except that the dicarboxylic acid and glycol components used and the amount of copolymerization were changed. A polymerized polyester was obtained. Next, an aqueous polyester dispersion and a coating liquid were prepared in the same manner as in Example 1 except that these copolyesters were used. Further, a biaxially stretched primer-coated polyester film was obtained in the same manner as in Example 1 except that these coating solutions were used. The adhesiveness, chargeability and surface property of the treated surface of this film were measured. The results are summarized in Table 1.

Comparative Example 1 Glass transition temperature of the composition shown in Table 1 was carried out in the same manner as in Example 1 except that 2,3'-disodium sulfobisphenol A ethylene oxide 2 mol adduct was not used.
A copolyester of ℃ was obtained. Next, an attempt was made to prepare a polyester aqueous dispersion in the same manner as in Example 1 except that these copolymerized polyesters were used, but water dispersion could not be achieved.

Comparative Examples 2 to 4 Example 3 except that dimethyl 5-sodium sulfoisophthalate was used in place of 2,3'-disodium sulfobisphenol A ethylene oxide 2 mol adduct and the copolymerization ratio was changed. A copolymerized polyester having a composition shown in Table 1 and a glass transition temperature of 29 ° C. was obtained in the same manner as in. Next, an aqueous polyester dispersion and a coating liquid were prepared in the same manner as in Example 1 except that these copolyesters were used. Further, a biaxially stretched primer-coated polyester film was obtained in the same manner as in Example 1 except that these coating solutions were used. The adhesiveness, chargeability and surface property of the treated surface of this film were measured. The results are summarized in Table 1. The amount of charge was large and not suitable for practical use.

Comparative Example 5 Same as Example 1 except that dimethyl 5-lithium sulfoisophthalate was used in place of 2,3'-disodium sulfobisphenol A ethylene oxide 2 mol adduct and the copolymerization ratio was changed. Then, a copolymerized polyester having a composition shown in Table 1 and a glass transition temperature of 27 ° C. was obtained.
Next, an aqueous polyester dispersion and a coating liquid were prepared in the same manner as in Example 1 except that these copolyesters were used. Furthermore, except that these coating liquids are used,
A biaxially stretched primer-coated polyester film was obtained in the same manner as in Example 1. The adhesiveness, chargeability and surface property of the treated surface of this film were measured. The results are summarized in Table 1. The amount of charge was large and not suitable for practical use.

Comparative Examples 6 and 7 The same procedures as in Example 1 were carried out except that the dicarboxylic acid and glycol components used and the copolymerization ratio thereof were changed, and the compositions shown in Table 1 were used at glass transition temperatures of 56 ° C. and 65 ° C. A copolyester was obtained. Next, an aqueous polyester dispersion and a coating liquid were prepared in the same manner as in Example 1 except that these copolyesters were used. Further, a biaxially stretched primer-coated polyester film was obtained in the same manner as in Example 1 except that these coating solutions were used. The adhesiveness, chargeability and surface property of the treated surface of this film were measured. The results are shown in Table 1.

Comparative Example 8 A glass transition temperature of 26 ° C. and a melting point of 223 ° C. of the composition shown in Table 1 were carried out in the same manner as in Example 1 except that the dicarboxylic acid, glycol component and the copolymerization ratio thereof used were changed.
A copolymerized polyester of Next, an attempt was made to obtain a polyester aqueous dispersion by the same procedure as in Example 1 except that these copolymerized polyesters were used. However, since the copolymerized polyester was insoluble in tetrahydrofuran, an aqueous dispersion could be obtained. There wasn't.

Comparative Example 9 Table 1 shows the characteristics of the biaxially oriented polyester film obtained in Example 1 without coating. The adhesive strength was low and it was not practically satisfactory.

[0051]

[Table 1]

Note: * 1 3,3'-Disodium sulfobisphenol A ethylene oxide 2 mol adduct * 2 Sodium sulfohydroquinone ethylene oxide 2 mol adduct * 3 3,3'-dilithium sulfobisphenol A ethylene oxide 2 mol Adduct * 4 3,3'-diphosphonium sulfobisphenol A
Ethylene oxide 2 mol adduct * 5 5-sodium sulfoisophthalic acid * 6 5-lithium sulfoisophthalic acid * 7 terephthalic acid * 8 isophthalic acid * 9 sebacic acid * 10 ethylene glycol * 11 trimethylene glycol * 12 bisphenol A ethylene oxide 2 Molar adduct * 13 Magnetic paint adhesion: ○ 90 g / cm or more × less than 90 g / cm

[0053]

EFFECT OF THE INVENTION According to the present invention, there are provided an aqueous polyester dispersion capable of forming an easily-adhesive coating film (primer layer) having less surface charge and excellent surface properties, and an easily-adhesive polyester film coated with the same. be able to.

Claims (2)

[Claims] 1. An aqueous polyester dispersion comprising a sulfoaromatic glycol component as a part of the glycol component and an aqueous dispersion of fine particles of an amorphous copolyester having a glass transition temperature of less than 55 ° C. body. 2. An easy-adhesion layer comprising a layer of an amorphous copolyester having a glass transition temperature of less than 55.degree. C. on at least one side of which a glycol component is partially composed of a sulfoaromatic glycol component. Polyester film.