JP3786614B2 - Method for producing low-charge and easy-adhesive polyester film - Google Patents

Description

【００５１】
【発明の効果】
本発明における易接着層（プライマー層）は、ポリエステル樹脂中に特定量のスルホン酸塩基を有することと、ポリエチレンオキシド・ポリプロピレンオキシドブロック共重合物及びポリエチレンオキシド・モノアルキルエーテルを特定量配合してあり、耐熱性に優れ高い接着性と低帯電性を発現する特長を有するとともに、塗工性も改善されたものであり、磁気記録媒体の基材として優れた特性を発現する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a low-charge / easily-adhesive polyester film. More specifically, the present invention is provided with a primer layer having excellent heat resistance and coating property, and having high adhesion and low chargeability. The present invention relates to a method for producing a low-charge and easy-adhesive polyester film useful as a substrate.
[0002]
[Prior art]
Polyester films have excellent physical and chemical properties and are used in a wide variety of applications (for example, magnetic recording media, graphic materials, printing materials, packaging materials, electronic materials, etc.). However, the polyester film has a high degree of crystallinity, and it is necessary to impart a surface characteristic suitable for the application in order to fully extract the film characteristic.
[0003]
As a means for imparting easy adhesion to a polyester film, it has been proposed and practically used to provide an easy adhesion layer (primer layer) by applying an aqueous liquid of an easily adhesive polyester resin, for example, an aqueous dispersion. For example, it is known to apply an aqueous liquid of a hydrophilic polyester resin in which 0.5 mol% or more of a sulfonate group is introduced into a polymer molecule. However, this hydrophilic polyester resin has a disadvantage that it has a low secondary transition point (Tg) and is inferior in heat-and-moisture resistance. In addition, a surfactant is added to stabilize the aqueous liquid or the coating process, but this surfactant also has a problem that the heat resistance is lowered and the coating property is poor.
[0004]
In order to increase the secondary transition point (Tg) of the polyester resin, it is effective to introduce a rigid component. In this case, however, the adhesive property tends to be lowered, and the hydrophilicity is also lowered. There is a problem that the solubility is lowered.
[0005]
In JP-A-63-115747, (A) formed from a mixed dicarboxylic acid component containing 0.5-15 mol% of a sulfonic acid metal base-containing dicarboxylic acid and a glycol component with respect to the total dicarboxylic acid component. Water-insoluble polyester copolymer and (B)
[Chemical 1]
_{HO- (R 1 O) n- (} R 2 O) m-H
(However, n and m are integers of 6 to 1200, R ₁ and R ₂ are alkylene groups having 1 to 4 carbon atoms or arylene groups, and _one of R ₁ and R ₂ is alkylene having 3 or more carbon atoms, or A transparent and antistatic thermoplastic resin film laminate characterized in that a layer having a copolymer mixture represented by (arylene group) is laminated on at least one surface of the film is disclosed. . However, it cannot be said that the antistatic property of this film laminate is sufficient, and since the copolymer has a low HLB, the adhesive properties tend to deteriorate.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a low-charge / easy-adhesive polyester film having excellent heat resistance and coating property, and having high adhesion and low chargeability.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the present invention has the following configuration.
[0009]
A water-dispersible polyester resin obtained by copolymerizing (A) a sulfonic acid metal base-containing compound in an amount of 0.01 mol% or more and less than 0.5 mol% per total acid component on at least one side of a polyester film, (B) polyethylene oxide / polypropylene It is characterized by applying a coating liquid containing an oxide block copolymer and (C) polyethylene oxide monoalkyl ether as a main solid component and drying to provide a primer layer having a softening point in the range of 140 to 170 ° C. A method for producing a low-charge and easy-adhesive polyester film.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0011]
In the present invention, the polyester constituting the polyester film is a polyester having aromatic dicarboxylic acid as the main acid component and aliphatic glycol as the main glycol component. Such polyesters are substantially linear and have film-forming properties, particularly film-forming properties by melt molding.
[0012]
Examples of aromatic dicarboxylic acids include terephthalic acid, naphthalene dicarboxylic acid, isophthalic acid, diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, and anthracene dicarboxylic acid. Can do.
[0013]
Examples of the aliphatic glycol include alicyclic groups such as polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol and the like, or cyclohexanedimethanol. A diol etc. can be mentioned.
[0014]
In the present invention, as the polyester, those mainly comprising alkylene terephthalate and / or alkylene naphthalate are preferably used. Among these polyesters, in particular, polyethylene terephthalate, polyethylene-2,6-naphthalate, 80 mol% or more of all dicarboxylic acid components are terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and 80 mol% or more of all glycol components. A copolymer in which is ethylene glycol is preferred. In this case, 20 mol% or less of the total acid component can be the above-mentioned aromatic dicarboxylic acid other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid, for example. Acid; can be alicyclic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid. Further, 20 mol% or less of the total glycol component can be the above-mentioned glycol other than ethylene glycol, and an aromatic diol such as hydroquinone, resorcin, 2,2-bis (4-hydroxyphenyl) propane; Aliphatic diol having an aromatic ring such as 1,4-dihydroxydimethylbenzene; polyalkylene glycol (polyoxyalkylene glycol) such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like.
[0015]
In the polyester of the present invention, an oxycarboxylic acid component such as an aromatic oxyacid such as hydroxybenzoic acid or an aliphatic oxyacid such as ω-hydroxycaproic acid is added to the total amount of the dicarboxylic acid component and the oxycarboxylic acid component. It includes those copolymerized in an amount of 20 mol% or less.
[0016]
Further, the polyester in the present invention has a substantially linear amount, for example, 2 mol% or less based on the total acid component, and a tri- or higher functional polycarboxylic acid component or polyhydroxy compound component such as trimellitic acid. And those obtained by copolymerizing pentaerythritol and the like.
[0017]
The polyester is known per se and can be produced by a method known per se.
[0018]
The polyester preferably has an intrinsic viscosity of 0.4 to 0.9 determined by measurement at 35 ° C. as a solution in O-chlorophenol.
[0019]
The polyester in the present invention may contain inert inorganic particles or crosslinked polymer particles as a lubricant alone or in any combination. As the inert inorganic particles, kaolin, calcium carbonate, silica, aluminum sesquioxide and the like are preferable. As the crosslinked polymer particles, particles composed of a crosslinked silicone resin, a crosslinked polystyrene resin, a crosslinked acrylic resin or the like are preferable. These particles are usually used as a reaction system, preferably as a slurry in glycol, at any time during polyester production, for example, at any time during the transesterification or polycondensation reaction by the transesterification method, or by the direct polymerization method. Add in. The average particle size of the lubricant is preferably 0.005 to 2 μm, more preferably 0.01 to 1.8 μm, and the addition amount is 0.01 to 2% by weight, more preferably 0.03 to 1.5% by weight. It is preferable that
[0020]
The polyester film in the present invention is preferably a biaxially oriented film, and the thickness is preferably 3 to 75 μm. Furthermore, the polyester film preferably has a biaxial Young's modulus of 450 kg / mm ² or more and 2000 kg / mm ² or less, respectively.
[0021]
The polyester film can be produced by a conventionally known production method or a production method accumulated in the industry.
[0022]
In the present invention, the primer layer provided on at least one surface of the polyester film is (A) water dispersibility obtained by copolymerizing 0.01 mol% or more and less than 0.5 mol% of a sulfonic acid metal base-containing compound per total carboxylic acid component. Polyester resin, (B) Polyethylene oxide / polypropylene oxide block copolymer and (C) Polyethylene oxide / monoalkyl ether are applied as a main solid component and dried to obtain a softening point of 140 to 170 ° C. It is a primer layer in the range of.
[0023]
In the water dispersible polyester resin (A), the sulfonic acid metal base-containing compound is 0.01 mol% or more and less than 0.5 mol%, preferably 0.04 to 0.3 mol%, based on the total dicarboxylic acid component. Copolymerized. If the copolymerization ratio of this compound is less than 0.01 mol%, the water dispersibility of the resin and the stability of the coating solution are very poor, while if it is 0.5 mol% or more, the chargeability of the film is strong, The purpose of low chargeability cannot be achieved.
[0024]
Examples of the sulfonic acid metal base-containing compound include dicarboxylic acids having a sulfonate group (for example, Na sulfonate, Li sulfonate, K sulfonate, ammonium sulfonate, polyalkylphosphine sulfonate, etc.), such as 5-Na sulfoisophthalic acid, 5-K sulfone. Preferable examples include isophthalic acid, 5-Na sulfoterephthalic acid, and 5-K sulfoterephthalic acid.
[0025]
Examples of the dicarboxylic acid component constituting the water-dispersible polyester resin (A) include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, hexahydroterephthalic acid, 4,4′-diphenyldicarboxylic acid, and phenyl. Indane dicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, etc., and glycol components include ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexane Examples thereof include dimethanol, dimethylolpropionic acid, glycerin, trimethylolpropane, and an alkylene oxide adduct of bisphenol A. Two or more of these can be used.
[0026]
The water-dispersible polyester resin (A) can be produced by a conventionally known method. And it is preferable that the number average molecular weights of water-dispersible polyester resin (A) are 3000-30000, Furthermore, 5000-15000. The water-dispersible polyester resin (A) is used as an aqueous dispersion during preparation of the coating liquid, and the average particle size of the aqueous dispersion is preferably several tens of nm.
[0027]
The polyethylene oxide / polypropylene oxide block copolymer (B) is represented by the following formula (1):
[0028]
[Chemical 2]
_{HO- (C 2 H 4 O)} n- (C 3 H 6 O) m- (C 2 H 4 O) p-H ...... (1)
A block copolymer having both ends composed of polyethylene oxide units, such as a block copolymer represented by
[0029]
In said formula (1), m is 20-80, n + p is 80-600, Furthermore, it is preferable that it is 100-600. N and p are each preferably 20 or more.
[0030]
The ratio of the polyethylene oxide unit and the polypropylene oxide unit in the polyethylene oxide / polypropylene oxide block copolymer (B) can be arbitrarily adjusted, but the ratio of the polyethylene oxide unit is 50 to 90% by weight, more preferably 70 to 70%. It is preferably in the range of 85% by weight. Further, the number average molecular weight of the block copolymer is preferably 5,000 to 30,000.
[0031]
The polyethylene oxide monoalkyl ether (C) is represented by the following formula (2):
[0032]
[Chemical 3]
_{RO- (C 2 H 4 O)} q-H ...... (2)
Here, R is an alkyl group, and q is a number from 3 to 15.
It is an ether compound represented by these. In this formula (2), the alkyl group of R is preferably a primary or secondary alkyl having 8 to 18 carbon atoms, and specific examples include octyl, lauryl, myristyl, pentadecyl, stearyl and the like. Among these, alkyl having 12 to 14 carbon atoms is particularly preferable. Moreover, q is preferably a number from 5 to 9. In the above formula (2), the alkyl group of R acts as a lipophilic component,
[0033]
[Formula 4]
_{- (C 2 H 4 O)} q-H
Acts as a hydrophilicity-imparting component. For this reason, although depending on the molecular weight of the alkyl group, those having a small degree of addition polymerization of ethylene oxide (in other words, having a small q) are strongly lipophilic, while those having a large degree of addition polymerization (in other words, q is Larger ones are more hydrophilic. In the balance of both characteristics, R is preferably an alkyl group having 12 to 14 carbon atoms, and q is preferably 5 to 9.
[0034]
In the present invention, the ratio (% by weight) of the water-dispersible polyester resin (A), the polyethylene oxide / polypropylene oxide block copolymer (B) and the polyethylene oxide / monoalkyl ether (C) is 93-80: 15-5: It is preferably 10 to 2, particularly 90 to 80:13 to 7: 7 to 3. When the proportion of the water-dispersible polyester resin (A) exceeds 93% by weight, the coating stability becomes poor, while when it is less than 80% by weight, the adhesiveness becomes poor. When the proportion of the polyethylene oxide / polypropylene oxide block copolymer (B) exceeds 15% by weight, the blocking resistance of the film is lowered. On the other hand, when the proportion is less than 5% by weight, the low chargeability, heat resistance and coating property are poor. Become. Further, when the ratio of the polyethylene oxide monoalkyl ether (C) exceeds 10% by weight, the heat resistance is lowered, whereas when it is less than 2% by weight, the coating property becomes poor.
[0035]
The primer layer in the present invention has a softening point in the range of 140 to 170 ° C, preferably 146 to 165 ° C. When the softening point is less than 140 ° C., the heat resistance is poor, and the heating roll in the film production process or processing process is soiled. On the other hand, when the softening point exceeds 170 ° C., the adhesiveness and the coating property deteriorate.
[0036]
The primer layer is provided by applying a coating solution to an unstretched polyester film, a uniaxially stretched polyester film, or a biaxially stretched polyester film and drying it. This application is performed on one or both sides of the film. Among these, it is preferable to apply a uniaxially stretched film stretched in the longitudinal direction. In this case, it is possible to carry out lateral stretching after coating, and in some cases, re-longitudinal stretching or re-lateral stretching. Stretching can be performed by conventionally known conditions and methods. For example, the draw ratio is 2.5 times or more, preferably 3.0 times or more in the biaxial direction, and the area ratio is 8 times or more, preferably 8 to 30 times.
[0037]
The solid content concentration of the coating solution (primer coating solution) is preferably 30% by weight or less, and more preferably 15% by weight or less. The solid concentration is preferably 0.5% by weight or more, more preferably 1% by weight or more. In addition to the water-dispersible polyester resin (A), the polyethylene oxide / polypropylene oxide block copolymer (B) and the polyethylene oxide / monoalkyl ether (C), other components such as inert fine particles are optionally added to the coating solution. , Heat stabilizers, and the like. The thickness of the primer layer (dry coating) is arbitrary, but is preferably 0.005 μm to 1 μm.
[0038]
The laminated polyester film thus obtained is excellent in coatability, adhesiveness, heat resistance and low chargeability and is particularly useful as a base material for magnetic recording media.
[0039]
【Example】
Hereinafter, the present invention will be further described with reference to examples. Each characteristic value was measured by the following method.
[0040]
1. The following coating material for evaluation is applied on the primer layer of the adhesive polyester film with a Meyer bar so that the thickness after drying becomes about 4 μm, and dried at 100 ° C. for 3 minutes. Thereafter, aging was performed at 60 ° C. for 24 hours, and then Scotch tape No. A 600 (made by 3M) width 12.7 mm and a length of 15 cm are adhered so that air bubbles do not enter, and this is leveled with a manual load roll described in JIS C2701 (1975), closely adhered, and cut into a tape width. The peel strength when this is peeled 180 degrees is measured.
○: 50 g or more Δ: 30 g or more and less than 50 g ×: 30 g or less
(Evaluation paint)
1 in terms of solid content Urethane resin Nipponporan 2304 25 parts by weight (made by Nippon Polyurethane)
▲ 2 ▼ PVC / Vinyl resin Resc A 50 parts by weight (manufactured by Sekisui Chemical)
(3) Dispersant Recion P 1 part by weight (made by Riken Vitamin)
(4) 500 parts by weight of magnetic agent CTX-860 (manufactured by Toda Chemical)
Is dissolved in a methyl ethyl ketone / toluene / cyclohexanone mixed solvent to make a 40% solution, and dispersed with a sand grinder for 2 hours. Thereafter, 25 parts by weight of the cross-linking agent Coronate L (in terms of solid content) is added and stirred well to obtain a magnetic paint.
[0042]
2. A dried product of the coating solution for the ring and ball type softening point primer layer is prepared, and the softening point is measured according to JIS K-3531-1960. The heating bath solution uses glycerin, and the rate of temperature rise is about 5 ° C./min.
[0043]
3. Using a heating roll heated to 110 ° C. and having a rotating surface speed of 4 m / min, a polyester film was run so that the primer layer surface was in contact with the heating roll at a nip pressure of 2 kg / cm ² , and the roll surface was evaluated after 40 minutes. .
○: No foreign matter is found on the roll surface Δ: Some foreign matter is seen on the roll surface ×: A large amount of foreign matter is seen on the roll surface [0044]
4). A chargeable polyester film (10 μm × 500 mm × 3000 m) is rewound at a speed of 150 m / min in an atmosphere of 23 ° C. × 75% RH, and the peel charge amount of the roll is measured by digital test electric measurement manufactured by Hugle Electronics Co., Ltd. Measurement is performed using a model Model-203.
[0045]
5. When the primer coating solution is coated on the film, the coated surface of the coat film is observed to determine whether it is uniformly applied.
○: Spots and muscles are not seen Δ: Slight spots and muscles are seen ×: Spots and muscles are very frequently observed
6). Coating solution stability The coating solution for primer is stored at 60 ° C. for 3 days and observed for precipitates.
○: No precipitate is seen Δ: A slight amount of precipitate is seen ×: A very large amount of precipitate is seen [0047]
[Example 1]
Preparation of primer coating solution:
2,6-naphthalenedicarboxylic acid component (40 mol%), isophthalic acid component (59.95 mol%), 5-Na sulfoisophthalic acid component (0.05 mol%), ethylene glycol component (70 mol%), bisphenol 82.5% by weight of a water dispersible polyester resin comprising a propylene oxide 4 mol adduct component (30 mol%) of A and having a number average molecular weight of about 10,000
Polyethylene oxide (80% by weight) / polypropylene oxide (20% by weight) block copolymer (number average molecular weight: about 23500) 12.5% by weight
Polyethylene oxide monoalkyl ether (number average molecular weight: about 500, alkyl group: mixed alkyl having 12 to 14 carbon atoms) 5% by weight
These were mixed well with an aqueous medium to prepare a primer aqueous coating solution having a solid concentration of 10% by weight.
[0048]
Production of polyester film:
An unstretched polyethylene terephthalate sheet having an intrinsic viscosity of 0.62 was stretched 2.3 times in the machine direction, and the primer aqueous coating solution was coated on one side thereof with a roll coater. Next, while being dried, the film was stretched 3.7 times in the transverse direction, further stretched 2.3 times in the longitudinal direction, and heat-set at 220 ° C. to obtain a film having a thickness of 10 μm. The thickness of the primer layer was 0.015 μm. Table 1 shows the characteristics of the film.
[0049]
[Examples 2 to 4, Comparative Examples 1 to 4]
In Example 1, it carried out similarly except having changed the polyester resin component into 85 weight% and changing the ratio of a coated material as shown in Table 1. The properties of the obtained film are shown in Table 1.
[0050]
[Table 1]

[0051]
【The invention's effect】
The easy-adhesion layer (primer layer) in the present invention has a specific amount of a sulfonate group in the polyester resin and a specific amount of polyethylene oxide / polypropylene oxide block copolymer and polyethylene oxide / monoalkyl ether. It has excellent heat resistance, high adhesiveness and low chargeability, and improved coatability, and exhibits excellent properties as a base material for magnetic recording media.

Claims (6)

93 to 80% by weight of a water dispersible polyester resin obtained by copolymerizing (A) a sulfonic acid metal base-containing compound of 0.01 mol% or more and less than 0.5 mol% per total acid component on at least one surface of the polyester film, A coating solution containing 15 to 5% by weight of a polyethylene oxide / polypropylene oxide block copolymer and 10% to 2% by weight of (C) a polyethylene oxide / monoalkyl ether as a main solid component is applied and dried to have a softening point of 140. A method for producing a low-charge and easy-adhesive polyester film, comprising providing a primer layer in a range of ˜170 ° C. A water-dispersible polyester resin obtained by copolymerizing (A) a sulfonic acid metal base-containing compound in an amount of 0.01 mol% or more and less than 0.5 mol% per total acid component on at least one side of a polyester film, (B) polyethylene oxide / polypropylene The main solid component is an oxide block copolymer and (C) polyethylene oxide monoalkyl ether . When kept at 60 ° C. for 3 days, a coating solution having no precipitate is applied and dried, and the softening point is 140 to A method for producing a low-charge and easy-adhesive polyester film, comprising providing a primer layer in a range of 170 ° C.   The low-charge / easy-adhesion property according to claim 1, wherein the copolymerization ratio of the sulfonic acid metal base-containing compound of the water-dispersible polyester resin (A) is in the range of 0.04 to 0.3 mol% per total acid component. A method for producing a polyester film.   The method for producing a low-charge / highly-adhesive polyester film according to claim 1, wherein the ratio of the polyethylene oxide component of the polyethylene oxide / polypropylene oxide block copolymer (B) is in the range of 50 to 90% by weight.   The method for producing a low-charge and easy-adhesive polyester film according to claim 1, wherein the carbon number of the alkyl of the polyethylene oxide monoalkyl ether (C) is 12 to 14.   The method for producing a low-charge and easy-adhesive polyester film according to claim 1, wherein the thickness of the polyester film is 3 to 75 µm, and the thickness of the primer layer is 0.005 to 1 µm.