JPH04173228A - Manufacture of easy bonding high strength polyester film - Google Patents

Abstract

PURPOSE:To manufacture a film having a primer layer of superior bonding properties to a magnetic coating material and no viscosity by applying aqueous coating liquid forming a film having the ring and ball softening point of more than the specified temperature, drying, orienting in the lateral direction, reorienting in the vertical direction and lateral direction and heat fixing. CONSTITUTION:Aqueous coating liquid containing copolymerized polyester as an easy bonding properties imparting component and forming a film having the ring and ball softening point of 120 deg.C or over is applied to at least one face of a polyester film oriented in the vertical direction. Drying and orienting in the lateral direction are carried out, and further reorienting in the vertical direction and reorienting in the lateral direction, if desired, and heat fixing are performed. The percent of stretch in the lateral direction is preferably two times or more, and its upper limit is perferably six times or less. The percent of reorientation is two times or more and its upper limit is preferably approximately 4.6 times. When the ring and ball softening point of the film is lower than 120 deg.C, the transfer of the film to a hot roll is generated, while when the degree of orientation of the film is too small, the breakage or falling- off of the film is generated at the time of reorientation, and fallen-off materials are adhered and piled up on guide rolls.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for producing an easily adhesive, high-strength polyester film, and more particularly, it relates to a method for producing an easily adhesive, high-strength polyester film, and more particularly to a method for producing an easily adhesive, high-strength polyester film, and more specifically, a method for producing an easily adhesive, high-strength polyester film. The present invention relates to a method for producing a high-strength polyester film useful as a base material for recording media.

<Prior Art> It is known to melt-extrude thermoplastic polyesters, such as polyethylene terephthalate or its copolymers, polyethylene naphthalate or its copolymers, or blends of these with small proportions of other resins, to form films. be. 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.

The above-mentioned polyester film is usually produced by a simple two-wheel stretching method, that is, simultaneous or sequential stretching in the longitudinal and transverse directions, followed by high-temperature heat setting.

Further improvement in strength of polyester film is desired depending on the application, and for this purpose, a method for manufacturing high-strength polyester film is to biaxially stretch in the longitudinal and transverse directions and then longitudinally stretch again (re-longitudinal stretching method). ) have been proposed (Special Publication No. 34-5EI87, Special Publication No. 36-2258, etc.)
. In this longitudinal re-stretching method, for example, a biaxially stretched polyester film is longitudinally re-stretched at a stretching temperature of 120 to 180°C and a stretching ratio of 1.2 times or more (in some cases, transverse stretching is further performed). Longitudinal re-stretched film has the advantage that its mechanical strength in the longitudinal direction is dramatically improved by more than 1.5 times that of simple biaxially stretched film, and is particularly useful as a base for magnetic tapes, mainly video tapes. It is extremely useful as a film.

By the way, since the surface of polyester film is highly crystal oriented, the surface cohesiveness is high, and it can be used for example in paints,
Poor adhesion of adhesives, inks, etc.

Therefore, physical treatments such as corona treatment, ultraviolet ray treatment, plasma treatment, EB treatment, flame treatment, etc., or chemical treatments such as alkali, amine aqueous solution, trichloroacetic acid phenol, etc. are known as methods for improving this adhesion. It is being

However, these methods have practical disadvantages such as deterioration of adhesive strength over time and contamination of the working environment due to volatilization of chemicals.

Another known method is to provide a brimer layer by applying an easily adhesive coating to the surface of the film in a process other than the usual polynisder film forming process.

However, with this method, organic solvents are usually used as coating solvents, and the coating atmosphere is not sufficiently clean, resulting in frequent surface defects on processed products due to dust adhesion, or environmental pollution caused by organic solvents. There are safety and hygiene problems such as deterioration.

By the way, if this brimer treatment is performed during the polyester film forming process using a water-based coating agent, there will be no dust adhesion in a clean environment, and since the film is a water-based solvent, there will be no risk of explosion or environmental deterioration. It has advantages in terms of performance, economy, and safety.

<Purpose of the Invention> In order to improve the adhesion of high-strength polyester films, the present inventor has developed an easy-adhesion brimer coating solution used in the simple biaxial stretching method after the first longitudinal stretching step in the longitudinal re-stretching method. When applied, it became clear that during the second stage of longitudinal stretching (re-longitudinal stretching), the coating film was transferred to the hot roll and the coating film broke and fell off due to re-stretching. As a result of further studies to solve this problem, the inventors of the present invention discovered that a special adhesion imparting component was used and the ring and ball softening point of the coating film was 120°C or higher, and the present invention was achieved. .

The object of the present invention is to provide various coatings to be applied to polyester films without transferring or falling off the coating film during the manufacturing process.
For example, Offsera 1 ink, gravure ink, silk screen ink, UV ink.

magnetic paints, gelatin compositions, adhesives, electrophotographic toners,
Chemical matte paint, diazo paint, hard coat paint,
Easily adhesive high-strength polyester film that has excellent adhesion to paints, heat-sealable compositions, free film-forming substances, etc., especially magnetic paints, and has a non-adhesive brimer layer. The purpose of this invention is to provide a method for manufacturing the same.

<Structure/Effects of the Invention> According to the present invention, at least one side of a longitudinally stretched polyester film contains a copolymerized polyester resin as an adhesion-imparting component, and has a ring and ball softening point of 120. Applying an aqueous coating solution that forms a coating film at a temperature of ℃ or higher, followed by drying, stretching in the transverse direction, further stretching in the longitudinal direction, re-stretching in the transverse direction if desired, and heat setting. This is achieved by a method for producing an easily adhesive, high-strength polynisder film characterized by the following.

In the present invention, the polyester constituting the polyester film is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. As a specific example of such a polyester, polybutylene lenticule 1
-, polyethylene isophthalate, polybutylene ethylene phthalate-1~.

Examples include poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalene dicarpoxylate, etc., and also include copolymers of these or blends of these with small proportions of other resins. Among such polyesters, those with a secondary transition point (Tg) of 60
~90°C is preferred.

The linear saturated polyester in the present invention is an agent that improves film properties, such as a lubricant and an antistatic agent.

It can contain colorants, flame retardants, light shielding agents, stabilizers, ultraviolet absorbers, and the like. This lubricant includes internal precipitated particles,
Any of the externally added particles may be used, or a combination of two or more types may be used. Examples of externally added particles include silica, kaolin, calcium carbonate, calcium phosphate,
Examples of the internally precipitated particles include those precipitated during the production of polyester using a combination of alkaline earth metal compounds, phosphorus compounds, and the like.

The polyester used in the present invention is known per se and can be produced by a known method.

Intrinsic viscosity of polyester (O-chlorophenol.

35°C) is preferably 0.45 to 0.9.

In the present invention, an amorphous unstretched film can be obtained by melt-extruding polyester and rapidly solidifying it by a conventional method. This unstretched film is first stretched in the machine direction, and then stretched in the transverse direction. These stretchings are performed by running the film. As the stretching means in the longitudinal and lateral directions, known means can be used. For example, stretching in the longitudinal direction (longitudinal stretching) is performed by heating the unstretched film with a group of heating rolls and utilizing the difference in circumferential speed between the low-speed roll and the high-speed roll.

At that time, it is preferable to provide an infrared heater between the low speed roll and the high speed roll to heat the film to the stretching temperature, or the film may be heated to the stretching temperature using the low speed roll. This stretching in the longitudinal direction is carried out at a magnification of 1.5 to 2.7 times during normal operation. Further, the stretching in the lateral direction (lateral stretching) is performed using a tenter type stretching heat treatment apparatus. This lateral stretching is
If lateral stretching is not performed again, it is carried out at a predetermined magnification, but when lateral stretching is performed again, it is carried out at a lower magnification than the predetermined stretching ratio (total stretching ratio). A biaxially stretched film that is also stretched in the transverse direction is usually subjected to the above-mentioned method (hot fixation at a low temperature).

The biaxially stretched film thus obtained is further stretched at least in the longitudinal direction, in other words in the longitudinal direction, or in both the longitudinal and transverse directions, and then subjected to a heat (fixing) treatment.

This second longitudinal stretching (re-longitudinal stretching) can be performed in the same manner as the first-stage longitudinal stretching means described above, or can be performed by another method. For example, the longitudinal stretching of the negative stage can be performed using an infrared heating method, and the re-longitudinal stretching can be performed using a roll heating method. As a method for longitudinal re-stretching, an infrared heating method is more advantageous in terms of the process since the temperature of the heated rolls in contact with the coated material is lower. Further, the transverse stretching (re-transverse stretching) and heat (fixing) treatment are performed using a tenter-type stretching heat treatment apparatus. If the transverse stretching ratio is set to 1 in this tenter-type stretching heat treatment apparatus, a case in which re-transverse stretching is not substantially performed and only heat setting treatment is performed is also an embodiment of the present invention.

As can be understood from the above, the longitudinal stretching device, the transverse stretching device, the longitudinal re-stretching device, the final heat treatment device, etc. in the present invention are as follows.
Conventionally known materials can be used.

The lateral stretching ratio in the present invention is 2 times or more, more preferably 2.5 times or more1. In particular, 3 times or more is preferable. However, when performing re-transverse stretching, the above magnification can be determined in combination with the re-transverse stretching magnification. The upper limit of the transverse stretching ratio depends on the film properties, but is preferably 6 times or less, more preferably 5 times or less.

The magnification of longitudinal re-stretching depends on the mechanical strength of the film, etc.
It is preferably 2.0 times or more, more preferably 2.2 times or more. The upper limit of this magnification is preferably about 4.6 times. Also, -
The longitudinal stretching ratio (predetermined ratio) of each stage is 1.5 to 3.0 times, preferably 1.5 to 2.6 times.

The temperature of the final heat treatment is 150-240℃, furthermore 170-240℃.
Preferably, the temperature is selected from the range of 230°C. This time is usually several tens of seconds or less. Further, the stretching temperature can be a conventionally known temperature.

In the present invention, an aqueous primer coating liquid is applied after the first stage of longitudinal stretching, and the coating liquid contains a copolymerized polyester resin as an adhesion-imparting component.

This copolyester resin is an aqueous resin and is a substantially linear polymer synthesized from a polybasic acid or its ester-forming derivative and a polyol or its ester-forming derivative. The polybasic acid component of this polymer is terephthalic acid.

Isophthalic acid, phthalic acid, phthalic anhydride, 2.6-
Examples include naphthanenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, 1-limellitic acid, pyromellitic acid, and dimer acid. Two or more types of these components can be used.

Furthermore, in addition to these components, a small proportion of unsaturated polybasic acids such as maleic acid, fumaric acid, itaconic acid, etc., and hydroxycarboxylic acids such as p-hydroxybenzoic acid, p-(β-hydroxyethoxy)benzoic acid, etc. may be used. I can do it. The proportion of the unsaturated polybasic acid component and the hydroxycarboxylic acid component is at most 10 mol%, preferably 5 mol% or less.

In addition, as a polyol component, ethylene glycol, 1
, 4-butanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,6-
Hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol.

Dimedilolprobionic acid, glycerin, 1-rimedilolpropane, poly(ethylene oxide) glycol,
Examples include poly(tetramethylene oxide) glycol. Two or more types of these can be used.

Copolymerized polyester resins are copolymerized compounds containing hydrophilic groups such as organic sulfonates, carboxylates, diethylene glycol, polyethylene glycol, polydetramethylene glycol, etc. in their molecules, and are used as aqueous dispersions. It is advantageous to make a roar and preferable. Usually, trifunctional or higher-functional carboxylic acid is used to add the carboxylic acid salt, but since this carboxylic acid branches during the polymerization process and tends to gel, it is desirable to reduce the copolymerization ratio. In this respect, introduction of a hydrophilic group using a sulfonate, di]nidylene glycol, polyalkylene ether glycol, etc. is more advantageous since the problems associated with a carboxylate do not occur.

In order to introduce a sulfonate group into the polyester molecule, for example, 5-Na sulfoisophthalic acid, 5-ammonium sulfoisophthalic acid, 4-Na sulfoisophthalic acid, 4-methylammonium sulfoisophthalic acid, 2-
Na sulfoterephthalic acid, 5-sulfoisophthalic acid,
It is preferable to use sulfoisophthalic acid for 4-, and an alkali metal sulfonic acid salt or amine sulfonic acid salt compound such as sulfoisophthalic acid 2Na sulfosuccinic acid for 2-. The polyhydric carboxylic acid or polyhydric alcohol having a sulfone M salt group is 0.5 to 20 mol%, more preferably 1 to 18 mol%, of the total polycarboxylic acid component or polyhydric alcohol component.
It is preferable that the

In addition, in order to introduce a carboxylic acid group into the polyester molecule, for example, trimellitic anhydride can be used.

Compounds such as 1-limellitic acid, biromellitic anhydride, pyromellitic acid, 1-rimesic acid, cyclobutanetetracarboxylic acid, and dimethylolpropionic acid can be used. Further, a carboxylic acid salt can be obtained by neutralizing a carboxylic acid with an amine compound, ammonia, an alkali metal, or the like.

When introducing a hydrophilic group-containing compound into a polyester molecule, various known methods can be employed. To further explain the case of introducing a carboxylate or organic sulfonate group, for example,
Method for synthesizing polyester using a compound containing three or more carboxylic acid salts in the molecule as one component of the starting material, and then converting the free carboxyl groups in the polyester with ammonia,
There are methods such as neutralization in a medium with amines, alkali metal compounds, etc. To further explain the method (2), for example, trimellitic anhydride is used as a component of the poly-[sprue raw material to produce a polymer having free carboxyl groups in the side chain, and after the reaction is completed, aqueous ammonia is added to neutralize it. , can make water-based polyester. Preferably, the polyester is produced by a melt polymerization method.

The copolymerized polyester resin needs to have a ring and ball softening point of 120°C or higher, and if a wetting agent is used, the ring and ball softening point of the coating film must be 1.
A polyester resin with a temperature of 20°C or higher is used.

Further, it is preferable that the copolyester resin has stretch followability during re-stretching, and therefore, it is preferable that the elongation of the primer coating film is 100% or more, more preferably 150% or more at 120°C. If the ring and ball softening point of the coating film is lower than 120°C, transfer of the coating film to the hot roll will occur, which is not preferable.

Furthermore, if the elongation of the coating film is too small, the coating film may break and fall off during re-stretching, and the falling matter may adhere to and accumulate on the guide roll, which is not preferable.

It is preferable that the aqueous primer coating liquid in the present invention contains a wetting agent in order to improve the wettability to the polyester film. As the wetting agent, surfactants such as anionic surfactants, cationic surfactants, and nonionic surfactants are preferable, such as polyethylene oxide/polypropylene oxide block copolymers, polyoxyethylene alkylphenyl ether, polyoxy Ethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkanesulfonate, alkyl sulfate.

Examples include alkylbenzene sulfonates, alkyl sulfonates, alkyldiphenyl ether disulfonates, alkyl sulfosuccinates, quaternary ammonium chloride salts, and alkylamine hydrochlorides. The amount of wetting agent is 2 to 30 wt% of the total solid content of the primer.
is preferable, and more preferably 3 to 20 wt%. Furthermore, antistatic agents, for example, may be used within a range that does not impair the effects of the present invention.

Other additives such as ultraviolet absorbers, pigments, organic fillers, inorganic fillers, lubricants, antiblocking agents, crosslinking agents such as melamine, epoxy, aziridine, etc. can be mixed.

The solid content concentration of the aqueous coating liquid is usually 30% by weight or less,
More preferably, it is 10% by weight or less. The coating amount is 0.5 to 209, or even 1 to 10 g per running film.
is preferred.

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

For example, a roll coating method, a gravure coating method, a reverse coating method, a roll plush method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, etc. may be applied alone or in combination. This aqueous coating liquid may contain a small amount of an organic solvent for the purpose of aiding the stability of the coating liquid or the coatability of the coating liquid.

The polyester film coated with the aqueous coating solution and subjected to longitudinal stretching is dried, transversely stretched, and longitudinally stretched again.

This leads to processes such as heat fixation. For example, a longitudinally stretched polyester film coated with an aqueous coating solution is guided into a stenter, horizontally stretched, longitudinally stretched again, and heat-set. During this time, the coating solution dries and forms a continuous film on the film. Drying is preferably carried out before or during lateral stretching.

The high-strength polyester film with the primer layer obtained in this way has high strength characteristics and can be used in various coatings such as cellophane inks, magnetic paints, gelatin compositions, electrophotographic toner compositions, chemical matte paints, diazo paints, It exhibits high adhesion to a wide range of paints such as U-ink, particularly strong adhesion to magnetic paints, and has good anti-blocking properties with no stickiness.

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

Note that "parts" in the examples mean "parts by weight."

Moreover, each characteristic of the film was measured by the following method.

1. Apply the evaluation paint to the adhesive primer-coated polyester film using a Mayer bar so that the thickness after drying is approximately 4 μm.
Dry at 00°C for 3 minutes. After that, it was aged at 60°C for 24 hours, and then Scotch tape NCL600 (manufactured by 3M) 12.7 mm long and 15 cm long was adhered without air bubbles, and then JIS C2701 (19
75) Smooth and adhere tightly using a manual load roll as described above, and cut out to the tape width. The strength is measured when this is peeled off 180 degrees.

[Paint for evaluation] In terms of solid content, ■ Urethane resin Niraporan 2304 (manufactured by Nippon Polyurethane) 25 parts ■ Salt/vinyl acetate resin Eslec A (manufactured by Block Chemical) 50 parts ■ Dispersant Rezion P (manufactured by Riken Vitamin) 1 part ■ 500 parts of the magnetic material CTX-860 (manufactured by Toda Chemical Co., Ltd.) is dissolved in a mixed solvent of methyl ethyl kene/1-toluene/cyclohexanone to make a 40% solution and dispersed for 2 hours using a sand grinder. Thereafter, 1 to 25 parts (in terms of solid content) of Coronate, a crosslinking agent, is added and stirred thoroughly to obtain a magnetic paint.

2. After combining the front and back sides of the blocking polyester film,
cn+x Cut into 15cm squares and heat at 50℃ x 50%R
A load of 50 kg/cffl was applied for 17 hours in an atmosphere of l-1, and then the peel strength of this 10 cm+i] was measured. The peeling speed for this sharpening is 100 mm/min.

3. Ring and ball softening point Dry the aqueous coating solution to prepare a dried product of the aqueous binder and wetting agent, and measure the softening point according to JIS K-2531-1960. Glycerin is used as the heating bath liquid, and the heating rate is approximately 5°C/min.

4. Transferability test during hot stretching A film before longitudinal re-stretching is taken, and the transferability during hot stretching is evaluated using the hot stretching test machine shown in FIG. That is, the film before longitudinal re-stretching was set in the unwinder 1 shown in FIG. 1, and the film was heated to 120°C at a surface speed of 5 m/
min, and then the surface speed was 11'r.
It is stretched between a roll 3 cooled with water at rL/min and wound up with a winder 4. Continue this stretching for 1 hour (
After the transfer, the surface of the hot roll 2 and the surface of the nip roll 6 of the cooling roll 3 that are in contact with the brimer layer are observed to check for the presence or absence of transferred materials, and evaluated based on the following criteria.

There is no transferred material on the surface...○ Some transferred material is observed on the surface...△ A large amount of transferred material is observed on the surface...×Examples 1 to 4. Comparative Example 1 Polyethylene terephthalate 1-(
After drying the film (containing lubricant) at 170°C for 3 hours, it was melt-extruded at 280°C onto a rotating cooling drum maintained at 20°C to obtain an unstretched film with a thickness of 150Lt7rL, and then reduced by 2.0 times using an infrared heater method. - After stage stretching, the aqueous brimer solution shown in Table 1 was applied to one side of the longitudinally stretched film at a wet rate of 5y/m using the Kisco I~ method. Continued 10
The film was stretched 3.9 times in the transverse direction at 5°C, then heated to 120°C with hot rolls, and the second longitudinal stretching (re-longitudinal stretching) was carried out at a stretching ratio of 2.8 using the speed difference between the two sets of nip rolls.
The temperature was increased twice as much, and heat fixation was further performed at 215°C for 6 seconds. The film thickness at this time was 10 μm, and the thickness of the final brimer layer was 0.04 μm. The properties of this film are shown in Table 2.

Comparative Example 2 A plain longitudinally stretched film was obtained in exactly the same manner as in Example 1, except that no primer liquid was applied.

The properties of this film are shown in Table 2.

As is clear from Table 2 and Table 2, the easily adhesive polyester film of the present invention has no thermal transfer during longitudinal re-stretching, and has excellent adhesive properties.
It has excellent blocking properties.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a hot stretching test machine for evaluating the transferability of a primer layer. The symbols in Figure 1 are as follows. 1: Unwinder, 2: Heating roll 3: Cooling roll, 4: Winder 5.6: Nip roll Patent applicant Teijin Ltd. Patent attorney 1) Hiroshi Jun
Ri A -

Claims (1)

[Claims] 1. An aqueous coating liquid containing a copolymerized polyester resin as an adhesion-imparting component on at least one side of a polyester film stretched in the longitudinal direction and forming a coating film having a ring and ball softening point of 120°C or higher. An easy-to-adhesive high-strength polyester film that is coated, then dried, stretched in the transverse direction, further stretched in the longitudinal direction, re-stretched in the transverse direction if desired, and heat-set. Production method. 2. The method for producing an easily adhesive high-strength polyester film according to claim 1, wherein the elongation of the coating film at 120° C. is 100% or more.