JPS61233540A - Polyester film laminate and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a polyester film laminate and a method for producing the same, and more particularly to advanced ceramic products such as audio magnetic tape, video magnetic tape, computer magnetic tape, The present invention relates to a polyester film laminate having excellent adhesiveness and solvent resistance, useful as a base material for floppy disks, X-ray photographic films, etc., and a method for producing the same.

BACKGROUND OF THE INVENTION It is known to melt extrude and form films from thermoplastic polyesters, such as polyethylene terephthalate or its copolymers, polyethylene naphthalate or its copolymers, or blends thereof with small proportions of other resins. It is also known that the resulting two-wheel stretched and heat-set polyester film has better heat resistance, gas barrier properties, electrical properties, and chemical resistance than films made of other resins. However, since the surface is highly crystal oriented, the surface has high cohesion and poor receptivity to paints, adhesives, inks, etc.

Therefore, when a synthetic resin layer is provided on the surface of such a polyester film, for example, the surface of the film is subjected to a corona discharge treatment in order to strengthen the adhesion between the two.

A method is used in which the surface is activated by ultraviolet irradiation treatment, plasma treatment, or flame treatment and then coated with a synthetic resin coating. However, although these methods of activating the film surface can be expected to improve adhesion to the coating layer by increasing the secondary bonding force due to wetting,
Its activity decreases over time. Therefore, these means of activating the film surface are not necessarily satisfactory.

As another method for increasing the receptivity of the polyester film surface, an etching method has been proposed in which the surface is swollen or partially dissolved with various agents.

This involves etching the film surface by bringing it into contact with chemicals such as acid, alkali, amine aqueous solution, trichloroacetic acid, or phenols, thereby decomposing, dissolving, and relaxing the crystal orientation near the surface, and at the same time reducing cohesion. This is intended to increase the adhesiveness with the binder resin by reducing the adhesiveness, and its effect is most reliable, and the adhesiveness between the film and the layer provided thereon, such as a synthetic resin coating layer, becomes strong.

However, some of the chemicals used in this method are harmful and may be dangerous to handle, and there is a risk that volatile substances from the chemicals may be released into the atmosphere. There are various disadvantages from a practical point of view, such as the need to be careful.

As a method similar to this method, a primer layer (undercoat layer) is provided on the surface of the film in advance, a thin surface layer different from the base film is formed, and then a desired layer, such as a synthetic resin layer, is coated. be. When forming the undercoat layer, a coating process is usually performed in a process different from the polyester film forming process. However, highly processed products such as audio magnetic tape, video magnetic tape, and computer magnetic tape.

In applications where precision and delicate quality must be maintained, such as floppy disks, X-ray photographic film, photographic film for printing, and diazo microfilm, the resulting film may be contaminated with dust even if an easily adhesive surface is successfully formed. If surface defects are present, the base film cannot be used for these purposes, but this defect is likely to occur in this separate process. Therefore, it is desirable to perform the undercoating process in an atmosphere as free from dust as possible. There is a polyester film forming process that satisfies these conditions, and if undercoating is performed in this process, it will be possible to obtain a product that can be fully used for the above-mentioned advanced film processing products.

On the other hand, in the prior art, the method of modifying the surface of a polyester film into an easily adhesive surface by brimer treatment is often achieved by applying a composition dissolved in a solvent to the surface layer of the film. It's here. If such methods are carried out during film production, contamination of the surrounding environment by fugitive organic solvents.

The use of organic solvents should be kept to a minimum as much as possible, as this may lead to unfavorable conditions in terms of safety and hygiene and adversely affect the film forming process. Therefore, when performing in-line subbing treatment in the film forming process, it is preferable to use a composition using water as a solvent from the viewpoints of process, economy, and safety. Therefore, many brimer compositions using water as a solvent have been proposed, and in particular, many proposals have been made for aqueous solutions or dispersions of polyurethane or polyester.

For example, Japanese Patent Publication No. 46-10193 discloses the use of polyurethane having solvent resistance to acetone and water dispersibility.

However, these brimer compositions swell or dissolve in solvents used in magnetic coatings, such as methyl ethyl ketone, cyclohexanone, tetrahydrofuran, etc., and are insufficient in terms of solvent resistance. When a highly polar paint such as a magnetic paint is applied on such a single layer of primer, the primer layer and the magnetic layer are mixed, which not only reduces the adhesion effect of the single layer of primer, but also causes flow on the surface of the coated layer. A good coated surface cannot be obtained.

Particularly in recent years, recording densities have been increasing in coated magnetic recording media, and magnetic layers are becoming thinner. In particular, the film thickness of floppy disks has been rapidly reduced to about 1 μ7 FL.

When the magnetic layer becomes thin like this, it is not preferable because the above-mentioned flow that occurs on the surface of the magnetic layer makes it difficult to obtain a good magnetic surface and causes deterioration of electromagnetic conversion characteristics.

OBJECTS OF THE INVENTION An object of the invention is various coatings applied to polyester films, such as cellophane inks.

Magnetic paints, gelatin compositions, offset inks.

It has excellent adhesion to electrophotographic toners, chemical matte paints, diazo paints, heat-sealable compositions, inorganic film-forming substances, etc., and does not cause peeling when these coatings are applied. It is an object of the present invention to provide a polyester film laminate coated with a single layer of primer having stable solvent resistance that is not affected by drying conditions of a coating solution. Another object of the present invention is to provide a preferred method for producing such polyester film laminates.

Components of the Invention According to the present invention, at least one surface of a polyester film is coated with two or more aqueous polyurethanes having at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half ester base. A polyester film laminate provided with a single layer of primer crosslinked with an epoxy compound having an epoxy group, and at least one side of the polyester film before crystal orientation is completed, containing carboxylic acid bases, sulfonic acid bases, and sulfuric acid half ester bases. A polyester film characterized by applying an aqueous brimer coating solution containing at least one aqueous polyurethane and an epoxy compound having two or more epoxy groups, followed by drying, stretching, and heat treatment to complete crystal orientation. This is achieved by a method for manufacturing a laminate.

In the present invention, polyester is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate,
Polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-
Examples include 2゜6-naphthalene dicarboxylate,
Copolymers of these or blends of these with small proportions of other resins are also included.

The polyester film of the present invention is obtained by melt-extruding such a linear saturated polyester resin, forming it into a film by a conventional method, and subjecting it to oriented crystallization and heat treatment crystallization. This polyester film is preferably crystal oriented to such an extent that the heat of crystal fusion measured by a scanning calorimeter in a nitrogen stream [at a heating rate of 10°C/min] is usually 4 cal/g or more. .

In the present invention, a polyester film before completion of crystal orientation refers to an unstretched film obtained by thermally melting the polymer and forming it into a film as it is; an unstretched film oriented in either the vertical direction or the horizontal direction. uniaxially stretched film: a two-wheel stretched film that is further stretched and oriented at a low magnification in both the vertical and horizontal directions, and then finally re-stretched in the vertical or horizontal direction to complete oriented crystallization), etc. This includes:

The aqueous brimer coating solution used in the present invention contains an aqueous polyurethane having at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base, and an epoxy compound having two or more epoxy groups. This aqueous polyurethane has an increased affinity for water with a carbonic acid group, a sulfonic acid group, or a sulfuric acid half ester group, and such water affinity-imparting groups are usually introduced after polyurethane synthesis. For example, a carboxylic acid group can be introduced by using a carboxylic acid group-containing polyhydroxy compound as one of the raw material poly and droxy compounds during polyurethane synthesis, or by introducing a hydroxyl group-containing carboxylic acid group into the isocyanate group of a polyurethane having unreacted isocyanate groups. This can be carried out by reacting an amino group-containing carboxylic acid, then adding the reaction product to an alkaline aqueous solution under high speed stirring, and neutralizing it. In addition, the introduction of a sulfonic acid group or a sulfuric acid half-ester base is usually carried out by forming a prepolymer from a polyhuman O-oxy compound, a polyisocyanate, and a chain extender, and then adding an amino group or a hydroxyl group that can react with the terminal isocyanate group and a sulfonic acid group to the prepolymer. Alternatively, it can be carried out by adding and reacting a compound having a sulfuric acid half ester base in its molecule, and finally obtaining an aqueous polyurethane having a sulfonic acid group or a sulfuric acid half ester base in its molecule. In this case, it is preferable to carry out the formation reaction in an organic solvent, then add water and then remove the solvent. Another method is to synthesize a polyurethane having a sulfonic acid group using a compound having a sulfonic acid group as one of the raw materials, and then add the polyurethane to an alkaline aqueous solution under high speed stirring to neutralize it. ,
Examples include a method of introducing an alkali sulfonic acid salt (for example, -303Na) by adding the following sultone compound to the primary or tertiary amino group of the main chain or side chain of polyurethane in the presence of an alkali. As the alkaline aqueous solution, it is preferable to use an aqueous solution of sodium hydroxide, potassium hydroxide, ammonia, alkylamine, etc., but the alkali does not remain in the coating film (undercoating film), such as ammonia, and amines that volatilize under drying conditions. Particularly preferred. The amount of base such as carboxylic acid base, sulfonic acid base, sulfuric acid half ester base, etc. is preferably 5 to 15% by weight. If the proportion of the base is too small, the water affinity of the polyurethane will be insufficient, making it difficult to prepare a coating solution, and if it is too large, the inherent properties of the polyurethane will be impaired, which is not preferable. Such aqueous polyurethane forms a stable aqueous dispersion or aqueous solution using a dispersion aid if desired.

Examples of polyhydroxy compounds used in the synthesis of polyurethane include polyethylene glycol.

Polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5
-bentanediol, diethylene glycol, triethylene glycol, polycaprolactone, polyhexamethylene adipate.

Polyhexamethylene sebacate, polytetramethylene adipate, polytetramethylene sebacate.

Trimethylo-rubroban, trimethylolethane.

Examples include pentaerythritol and glycerin. Examples of the polyisocyanate compound include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, an adduct of tolylene diisocyanate and trimethylolpropane, an adduct of hexamethylene diisocyanate and trimethylolethane, and the like. Examples of carboxylic acid-containing polyols include dimethylolpropionic acid and dimethylolbutyric acid.

Examples include dimethylolvaleric acid and trimellitic acid bis(ethylene glycol) ester. Examples of the amino group-containing carboxylic acid include β-aminopropionic acid, γ-aminobutyric M, and P-aminobenzoic acid. As the hydroxyl group-containing carboxylic acid, for example, 3
-Hydroxypropionic acid, γ-hydroxybutyric acid, P
-(2-hydroxyethyl)benzoic acid, malic acid, etc. can be mentioned. Examples of compounds having an amino group or a hydroxyl group and a sulfonic group include aminomethanesulfonic acid, 2-aminoethanesulfonic acid, and 2-amino-5-methylbenzene-2-sulfonic acid.

Sodium β-hydroxyethanesulfonate, aliphatic diprimary amine compound propane sultone.

Examples include butane sultone adducts, preferably propane sultone adducts of aliphatic diprimary amine compounds. Furthermore, examples of compounds containing an amino group or a hydroxyl group and a sulfuric acid half-ester group include amine ethanol sulfuric acid, ethylenediamine ethanol sulfuric acid, aminobutanol sulfuric acid, hydroxyethanol sulfuric acid, γ-hydroxypropanol sulfate, α-hydroxyethanol sulfuric acid, etc. .

Polyurethane can be synthesized using these compounds by conventionally well-known methods.

As the epoxy compound having two or more epoxy groups that crosslinks with the aqueous polyurethane, aliphatic epoxy compounds such as (Shiochimushiro), -1 to 13, n-1 to 13, 0H, -○H are preferred. can give.

The aqueous primer coating liquid used in the present invention may be an aqueous solution or an aqueous dispersion, and is not particularly limited. The ratio of the aqueous polyurethane to the epoxy compound is preferably 1 to 40 parts by weight, more preferably 2 to 30 parts by weight, to 100 parts by weight of the former. If the ratio of the epoxy compound is too high (too much, it will reduce the adhesive properties), and if it is too low, the solvent resistance will be lowered, making it difficult to obtain a good coated surface when the coating is applied, which is the object of the present invention, which is undesirable. .

The cross-linking reaction between aqueous polyurethane and epoxy compound proceeds even at low temperatures. Therefore, the primer composition 1 of the present invention has the advantage that even if the heating conditions such as drying of the coating solution are insufficient, the crosslinking density increases with time, and a primer with constant solvent resistance 1 can always be obtained. attitude).

Is the water-based primer coating liquid sufficient for the above two limits in an aqueous medium? Although it is dissolved or dispersed, a necessary amount of a surfactant such as an anionic surfactant or a nonionic surfactant can be added thereto.

As such a surfactant, the surface tension of the aqueous coating solution is 40
(1yne/[), and those that promote wetting to polyester films are preferred, such as polyoxyethylene alkylphenyl ether.

Polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester.

Examples include fatty acid metal soaps, alkyl WNM salts, alkyl sulfonates, alkyl sulfosuccinates, quaternary ammonium chlorides, and alkylamine hydrochlorides. Furthermore, antistatic agents, ultraviolet absorbers, pigments, organic fillers, and inorganic fillers may be added within a range that does not impair the effects of the present invention.

Other additives such as lubricants, antiblocking agents, etc. can be mixed.

The aqueous primer coating solution may be applied to the polyester film in a normal coating process, that is, in a process in which it is applied to the two-wheel stretched and heat-set polyester film separately from the film manufacturing process.

However, this process tends to introduce dirt, dust, etc., and it is desirable to apply the coating in a clean atmosphere for advanced products such as magnetic tapes and floppy disks. From this point of view, coating during the polyester film manufacturing process is preferable. In particular, it is preferable to apply an aqueous brimer coating liquid to one or both sides of the polyester film before the crystal orientation is completed during this step. In this case, the fixed valve concentration of the aqueous primer coating liquid is usually 30% by weight or less, more preferably 10% by weight or less. The amount of the coating to be applied is preferably 0.5 to 20 g, more preferably 1 to 10 g per tail of the running film.

Any known coating method can be used as the coating method.

For example, a roll coating method, a gravure coating method, a roll plush method, a spray coating, an air knife coating, an impregnation method, a curtain coating method, etc. may be applied alone or in combination.

The polyester film coated with the aqueous coating solution is dried and subjected to processes such as stretching and heat setting. For example, a longitudinally uniaxially stretched polyester film coated with an aqueous primer coating solution is guided into a stenter, where it is laterally stretched and heat-set.

During this time, the coating solution dries and further undergoes a crosslinking reaction, forming a continuous film on the film. Heat for the crosslinking reaction is usually supplied by heat during stretching or heat setting. For example, 2
00°C for about 10 seconds, 150°C for about 1 minute, 120°C for about 15 minutes, 220°C for about 8 seconds, etc. (or heated under harsher or milder conditions). The coating solution may be dried at 100°C for about 5 seconds.

It may be heated at 110°C for about 5 seconds and at 90°C for about 20 seconds. It may also be air-dried.

Oriented crystallization conditions of polyester film, e.g. stretching,
Conditions such as heat fixation can be carried out under conditions conventionally accumulated in the art.

Effects of the invention The polyester film having the primer layer thus obtained can be used as an ink for cellophane.

magnetic paints, gelatin compositions, toner compositions for electrophotography,
It shows high adhesion to a wide range of paints such as Chemi and Calmat paints, and has excellent adhesion to methyl ethyl ketone, toluene,
Shows excellent solvent resistance to organic solvents such as ethyl acetate, butyl acetate, ethanol, dioxane, tetrahydrofuran, cyclohexanone, and cyclohexane.

Example The present invention will be further explained below with reference to Examples.

Note that "part J" in the examples means "part by weight." Moreover, each characteristic of the film was measured by the following method.

1. Coating for evaluation is applied to an adhesive brimer-coated polyester film, dried at 80°C for 1 minute, aged at 160°C for 24 hours, and roll coated to an average coating thickness of 2 μm. The resulting coated film is RCA
The adhesion is measured by the number of times of wear until a hole is formed on the coated surface when the head is worn with an abrasion tester (RCA) at a head load of 150 g.

[Adjustment of paint for evaluation] Nitrocellulose R81/2 as lacquer thinner for paint
[Freus containing 25% isopropanol; manufactured by Daicel ■] was dissolved to prepare a 40 wt% solution, and the solution was
3.9 parts followed by polyester resin (Desmofene #
1700: manufactured by Bayer) 32.5 parts, chromium dioxide magnetic powder 2.60 parts 9 Dispersant.

As a wetting agent, soybean oil fatty acid (Region P: manufactured by Riken Vitamin ■), cationic activator (cation AB Nippon Yushi @
1 part, 0.5 part, and 0.8 part of squalene (shark liver oil) were put into a ball mill. Mixed solution 2 consisting of methyl ethyl ketone (hereinafter abbreviated as MEK)/cyclohexanone/toluene = 3/4/3 (weight ratio)
Further, 82 parts of the mixture is further mixed and sufficiently pulverized to prepare a mother liquor paint (45 wt%). To 50 parts of this mother liquor, an addition reaction product of trimethylolpropane and tolulein diisocyanate (Conate L2 Nippon Polyurethane Kogyo ■
48 parts (manufactured by Manufacturer, Inc.) and 6.25 parts of butyl acetate were added to obtain a magnetic paint for evaluation with a final solid content concentration of 42.75 wt%.

2. Apply a drop of tetrahydrofuran (approximately 0.02 cc) to the surface of the polyester film coated with a solvent-resistant primer using a dropper.
Drop it, place gauze on top, place a 100 g weight on top, and move the gauze at a speed of about 1000 m/min. After drying at room temperature, interference micrographs of those not treated with tetrahydrofuran and those treated with tetrahydrofuran were compared at 400 times magnification, and the state of surface change of the primer was judged as follows.

Those with almost no primer: X with almost no change in primer 20 Those with a slight change in surface morphology in the middle 20 Those with a significant change in surface morphology: ×~Δ Those with an intermediate change in surface morphology :Δ Example 1 Polyurethane aqueous dispersion having carboxylic acid amine base [
Manufactured by Toyo Polymer @: Product name: Merci - 585,180 parts (
(as a non-volatile component), polyoxyethylene nonylphenyl ether [manufactured by NOF ■: product name NS-240]
10 parts and polyfunctional epoxy compound [Toyo Polymer @
:Product name: Merci AD-C-65] 10 parts was diluted with ion-exchanged water to prepare an aqueous primer coating solution with a solid content concentration of 2% by weight, and this coating solution was gravure coated on a two-wheel stretched polyethylene terephthalate film. Apply and then 140℃
Heat treated for 45 seconds in a drying zone, with an average coating weight of 5.
A brimer-coated polyester film laminate of OFF-〇 rV/Td was obtained.

The film laminate had sufficient adhesion to the magnetic paint for evaluation, and it was possible to form a good coated surface without running marks.

Example 2 Intrinsic viscosity measured in 0-chlorophenol at 25°C 0
．． 65 polyethylene terephthalate (containing lubricant) 2
Melt extruded onto a rotating cooling drum maintained at 0°C to a thickness of 9.
An unstretched film of 50t and tTrL was obtained, then stretched 3.5 times in the machine axis direction, and then a coating solution identical to the coating solution prepared in Example 1 was applied to both sides of the uniaxially stretched film using the kiss coating method. did. The average coating amount at this time was 50 .mu./-rrL in terms of solid content. Subsequently, the film was stretched 3.9 times in the transverse direction at 105°C and further heat-treated at 210°C to obtain a biaxially oriented polyester film laminate having a thickness of 75 μm and coated with double-sided brimer.

Example 3 Adipic acid, instead of the polyurethane aqueous dispersion of Example 2,
105O-3 in the molecule synthesized from sebacic acid, 08-valent 53 aliphatic polyester consisting of 1,5-bentanediol and neopentyl glycol components, hexamethylene diisocyanate, aminoethanol@acid half ester, and potassium hydroxide. % to 2.2wt% (solid content ratio)
A polyester film laminate was obtained in exactly the same manner as in Example 2, except that 80 parts of the aqueous polyurethane dispersion (as a non-volatile component) was used.

Example 4 A polyurethane dispersion containing a carboxylic acid amine base was used instead of the coating solution of Example 2 [manufactured by Dainippon Ink Industries @ trade name Hytran HW-1001].
A polyester film laminate was obtained in exactly the same manner.

Comparative Example 1 For comparison, various evaluations were performed using a 75 μm thick polyethylene terephthalate film that was not subjected to primer treatment.

Comparative Example 2 A polyester film laminate having a single primer layer containing no aqueous epoxy resin as a crosslinking agent was obtained by the method of Example 1 using only 90 parts of the aqueous polyurethane resin of Example 1 and 10 parts of polyoxynonylphenyl ether. .

Comparative Example 3 A primer coating solution was prepared in the same manner as in Example 1, except that the ratio of aqueous polyurethane resin/aqueous epoxy resin/polyoxynonylphenyl ether was 40 parts, 150 parts, and 10 parts, and the experiment was carried out using this coating solution. A polyester film laminate was obtained by the method of Example 2.

The coating material for evaluation was dry coated on the polyester film laminates obtained in Examples 1 to 4 and Comparative Examples 1 to 3 to a thickness of 1.5 mm.
It is coated and dried to a thickness of μm and has adhesive properties.

The coating properties and solvent resistance were evaluated. The results are shown in Table 1.

(Left below) Table 1/Polyoxynonylphenyl ether weight ratio From Table 1, it can be seen that the primer layer of the film laminate of the present invention has excellent performance in solvent resistance and adhesiveness, and does not cause streak rings during coating. It is clear that uniform and stable coating is possible without generation.

Procedural amendment February 8, 1985

Claims (1)

[Claims] 1. On at least one side of a polyester film, an aqueous polyurethane containing at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base is crosslinked with an epoxy compound having two or more epoxy groups. A polyester film laminate with a primer layer. 2. The laminate according to claim 1, wherein the base of the aqueous polyurethane is an amine base. 3. The laminate according to claim 2, wherein the amine base is a carboxylic acid amine base. 4. On at least one side of the polyester film before crystal orientation is completed, apply an aqueous polyurethane having at least one of a carboxylic acid group, a sulfonic acid group, and a sulfuric acid half-ester base and an epoxy compound having two or more epoxy groups. 1. A method for producing a polyester film laminate, which comprises applying an aqueous primer coating solution containing a polyester film, followed by drying, stretching, and heat treatment to complete crystal orientation. 5. The manufacturing method according to claim 4, wherein the base of the aqueous polyurethane is an amine base. 6. The manufacturing method according to claim 5, wherein the amine base is a carboxylic acid amine base.