JPH0326543A - Antistatic polyester film - Google Patents

Abstract

PURPOSE:To obtain an antistatic film having stable antistatic properties, excellent in transparency, flatness and easy slide properties and enhanced in close adhesiveness by providing a thin layer consisting of an acrylic resin, a copolymer polyester resin, fine particles with a specific mean particle size and an antistatic agent to the single surface of a polyester film. CONSTITUTION:The thin layer formed to at least the single surface of a polyester film consists of an acrylic resin A, a copolymer polyester resin B, fine particles C with a mean particle size of 0.5mum or less and an antistatic agent D. The ratio of the respective components forming the thin layer is set so that the total amount of the components A, B is 20-80wt.%, the amount of the component C is 5-40wt.% and the amount of the component D is 5-75wt.% and the ratio of the components A, B is set so that the former is 0.1-5 times the latter on a wt. basis. The thin layer is applied to the surface of the polyester film before the orientation crystallization process of the polyester film is completed as an aqueous coating solution. The concn. of the solid of the aqueous coating solution is usually set to 30wt.% or less and the viscosity thereof is set to 100cps or less. The coating amount thereof is set to about 0.5-20g/1m<2> of a running film.

Description

[Detailed description of the invention] Industrial application field> The present invention relates to an antistatic polyester film, and more specifically, the present invention relates to an antistatic polyester film that has a stable and low surface resistivity value, is transparent, flat, easy to slip, and is thin. Conventional technology regarding antistatic polyester films with excellent layer adhesion, etc. Resin films such as biaxially stretched and heat-set polyester films have excellent mechanical properties, heat resistance, gas barrier properties, chemical resistance, etc. , surface specific resistance value is 1014~1017Ω/
It has a large diameter and is easily charged, and if left as is, it tends to cause problems with foreign matter adsorption in magnetic recording media and electronic materials.

Conventionally, known methods for preventing electrification of films include a method of incorporating an antistatic agent such as lithium dodecylbenzenesulfonate into a pace polymerer, and a method of applying a low-molecular antistatic agent to the surface of the film. However, in the kneading method, the compatibility between the antistatic agent and polyester is poor, and when the amount of antistatic agent is kneaded in to exhibit antistatic properties, the film becomes opaque.
This is disadvantageous for HP films, etc. On the other hand, the coating method is excellent in terms of film transparency, but since the antistatic agent is low molecular weight, it is sticky and tends to cause films to block each other. Furthermore, if only an antistatic agent is applied, the adhesion to the base film is poor, and there is a drawback that, for example, cellophane tape or the like cannot be attached.

OBJECT OF THE INVENTION An object of the present invention is to provide an antistatic film that has stable antistatic properties, has excellent transparency, flatness, and slipperiness, and has high adhesion. .

Structure and Effects of the Invention> An object of the present invention is that according to the present invention, at least one side of a polyester film contains (A) an acrylic resin, (B)
This is achieved by an antistatic polyester film characterized by providing a thin layer consisting of a copolymerized polyester resin, (C) fine particles with an average particle size of 0.5 μm or less, and (D) an antistatic agent.

In the present invention, the polyester forming 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. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalene dilupoxylate, and copolymers of these polyesters. It also includes combinations or blends of these with small proportions of other resins.

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, the thin layer formed on at least one side of the polyester film consists of (A) acrylic resin, (B
) Copolymerized polyester resin, (C) average particle size 0.5 μm
It consists of the following fine particles and (D) an antistatic agent.

The (human) acrylic resin is, for example, an acrylic ester (alcohol residues include methyl group, ethyl group, n-
Methacrylic ester (alcohol residue are the same as above.>; Hydroxy-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxybrobyl methacrylate, etc.; Acrylamide, methacrylamide, N-methylmethacrylamide , N-methylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N
, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide, etc.; N,N-diethylaminoethyl acrylate, N,N-diethylaminoethyl methacrylate, etc. Amino group-containing monomers: Eboxy group-containing monomers such as glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, etc.; styrene sulfonic acid,
Monomers containing sulfonic acid groups or salts thereof, such as vinyl sulfonic acid and their salts (e.g., sodium salts, potassium salts, ammonium salts, etc.); crotonic acid,
Monomers containing carboxyl groups or salts thereof, such as itaconic acid, acrylic acid, maleic acid, fumaric acid, and their salts (e.g., sodium salts, potassium salts, ammonium salts, etc.); Monomers containing acid anhydrides; others: vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylic nitrile, alkyl itaconic acid monoester,
It is made from a combination of monomers such as vinylidene chloride, vinyl acetate, and vinyl chloride, but it contains 50 mol% or more of (meth)acrylic acid monomers such as acrylic acid derivatives and methacrylic acid derivatives. Preferably, those containing methyl methacrylate are particularly preferable. In addition, acrylic resin has a secondary transition temperature of 20~
90°C, more preferably 30 to 80°C.

Such acrylic resins can be self-crosslinked using functional groups within the molecule, or can be crosslinked using a crosslinking agent such as a melamine resin or an epoxy compound.

The acid components constituting the copolymerized polyester resin (B) include terephthalic acid, isophthalic acid, phthalic acid, 1,4
-Cyclohexanedicarboxylic acid, 2.6 naphthalene dicarboxylic acid, 4.4'-diphenyldicarboxylic acid, adibic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, 5-Na sulfoisophthalic acid, 2-K sulfoterephthalic acid, Examples include polyhydric carboxylic acids such as mellitic acid, trimesic acid, trimellitic anhydride, phthalic anhydride, p-hydroxybenzoic acid, and trimellitic acid monopotassium salt. In addition, hydroxy compound components include ethylene glycol, propylene glycol, 1.3-propanediol, 1.4-butanediol, 1.6-hexanediol, neopentyl glycol, 14-cyclohexanedimethanol, p-xylylene glycol, Bisphenol A-ethylene oxide adduct, diethylene glycol, triethylene glycol, polyethylene oxide glycol, polytetramethylene oxide glycol, dimethylolbrobionic acid, glycerin, trimethylolpropane, sodium dimethylolethylsulfonate,
Examples include polyhydric hydroxy compounds such as potassium dimethylolprobionate. Polyester resins can be produced from these compounds by conventional methods. When preparing an aqueous coating liquid, it is preferable to use a polyester resin containing a 5-Na sulfoisophthalic acid component or a carboxylic acid group.

Such a copolyester resin can be a self-crosslinking type having a functional group in the molecule, or can be crosslinked using a curing agent such as a melamine resin or an epoxy resin.

The fine particles (C) include, for example, polystyrene, polymethyl methacrylate, methyl methacrylate copolymer, crosslinked methyl methacrylate copolymer, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, penzoguanamine resin, etc. Organic fine powder; silica, alumina, titanium dioxide, kaolin,
Examples include fine inorganic powders such as talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black, barium sulfate, and the like. These may be in the form of an aqueous dispersion using an emulsifier or the like, or may be in the form of a fine powder that can be added to an aqueous liquid. Among these, organic fine powder and polymethyl methacrylate powder are preferred. Further, in order to prevent the fine particles from settling in the aqueous dispersion, it is preferable that the specific gravity does not exceed 3.

The average particle size of such fine particles is 0.5 μm or less.

Preferably it is 0.01 to 0.15 μm. When the average particle size is larger than 0.5 μm, transparency and abrasion resistance (durability)
decreases, which is not desirable.

The fine particles have the effect of promoting the uniform formation of microprotrusions on the coating film itself, and the reinforcing effect of the fine powder itself on the coating film, and further improve the blocking resistance of the resins (A) and (B) to the coating film. Combined with its effect on reducing frictional force and the synergistic effect of the two, it improves the scratch resistance of the coating film, giving the polyester film excellent slipperiness.

Furthermore, the antistatic agent (D) has a molecular weight of 500.
0 or more polymer type antistatic agents are preferred. For example, anionic polymer type antistatic agents using sodium methacrylsulfonate, 2-sodium sulfoethyl methacrylate, etc. are preferably used. In order to enhance this antistatic effect, a small amount of a low molecular weight antistatic agent may be used in combination.

In the present invention, the proportion of each component forming the thin layer is the total amount of component {A) and component (B), the amount of component (C), and the amount of component (D) of 20 to 80% by weight, 5% by weight, ~40% by weight, 5
Preferably, the proportion is between 75% and 75% by weight.

Further, 30 to 70% by weight, 5 to 40% by weight, 5 to 75% by weight
Preferably, it is in a proportion of % by weight. The ratio of component (A) to component (Bl) is preferably such that the former is 0.1 to 5 times the weight of the latter, more preferably 0.25 to 4 times the weight of the latter. Component +
A> and the ratio of component (B) is less than 0.1 times by weight,
The compatibility of component (DJ) decreases and the film surface becomes opaque, which is undesirable.Also, if the ratio of component (A) and component (B) is greater than 4 times by weight, the resistance of the antistatic layer (coating film) may be reduced. Scrapability is poor, and scraping powder adheres to the guide roll of the film running system, and the transfer of the scraping powder causes unevenness on the film surface.
It is not preferable because it becomes rough.

The thin layer in the present invention is preferably formed by applying a coating liquid during the manufacturing process of the polyester film. For example, it is preferable to apply an aqueous coating liquid to the surface of the polyester film before the oriented crystallization process is completed.

Here, the polyester film before the 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 that is oriented in either the longitudinal direction or the lateral direction. Uniaxially stretched film:
Furthermore, the biaxially stretched film is stretched at a low magnification in two directions, the longitudinal direction and the transverse direction, and then finally re-stretched in the longitudinal direction or the transverse direction to complete the oriented crystallization.
etc.

The film of the present invention is preferably produced by applying a coating solution of the above-mentioned composition to an unstretched film or a film stretched in at least one axis direction before completion of crystal orientation, and directly subjecting the film to longitudinal stretching and/or transverse stretching and heat setting. It is manufactured using the so-called in-line coating method. At that time, in order to ensure that the coating film can be smoothly applied to the surface of the polyester film before the oriented crystallization process is completed, the film surface is subjected to corona discharge treatment as a preliminary treatment, or a coating composition is applied. In addition, it is preferable to use a chemically inert surfactant together with this. Such a surfactant promotes wetting of the polyester film such that the surface tension of the aqueous composition can be lowered to 40 dyne/cm or less,
For example, anionic and nonionic surfactants such as polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfonate, alkyl sulfosuccinate, etc. Agents, etc. can be mentioned. Furthermore, other additives such as ultraviolet absorbers and lubricants may be mixed within the range that does not impair the effects of the present invention.

The solid content concentration of the above coating liquid, especially the aqueous coating liquid, is usually 30
It is not more than 15% by weight, preferably not more than 15% by weight. The viscosity is suitably 100 cps or less, preferably 20 cps or less. The amount of coating is approximately 0 per 1 film running.
．． 5 to 20 g, more preferably 1 to Log.

In other words, in the finally obtained biaxially stretched film, approximately 0.00 mm per lrrl' is applied to one surface of the film. ooi~
1g, and even about 0.01-0. A solids content of 3g is preferred.

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

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

According to a preferred production method of the present invention, the aqueous liquid is preferably applied to a polyester film immediately after being subjected to longitudinal uniaxial stretching, and then guided to a tenter for transverse stretching and heat setting.

At that time, the coated material is in the state of an unsolidified coating film whose area is expanded as the film is stretched, and the heated water is evaporated, resulting in a thin film with many microprotrusions on the surface of the biaxially stretched polyester film. The layers are firmly attached. This heat treatment is preferably carried out at a temperature of about 100 to about 240°C for about 1 to about 20 seconds.

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.

The polyester film of the present invention uses an acrylic resin and a copolymerized polyester resin as a binder, and coats the base film with a mixture of fine particles of a specific particle size, particularly organic fine particles, and mainly a polymer type antistatic agent. As a result, it has excellent adhesiveness, transparency, slipperiness, and antistatic properties, and is particularly useful as an OHP film, a sorter film, and the like. This film is
For example, it has a surface resistivity of 108 to 1013 Ω/mouth,
Moreover, this surface resistivity has a characteristic that it is hardly affected by the atmosphere. Furthermore, the paint film has excellent adhesion to the base film.

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

Note that "part" means part by weight, and the film properties were measured by the following method.

1. Aluminum was deposited on a film sample with a surface resistivity of 8 cm square, and heated to 23°C.
The surface specific resistance value (Ω/mouth) was measured using a high-voltage power supply resistor and a vibrating capacitance type microcurrent electrometer under conditions of , 60% RH.

2. Surface slippage IK between coated surfaces at a temperature of 23℃ and humidity of 60%RH
The static friction coefficient under g load is measured using a slippery measurement tester manufactured by Toyo Tester Co., Ltd.

3. After aligning the blocking coating film surfaces, cut into 10 cm x 5 cm squares, apply a load of 6 kg/cd to this in an atmosphere of 80% R}I at 60°C for 17 hours, and then check the peel strength of this 5 cm width. Measure. The peeling speed at this time was 100m.
m/min.

4. Surface roughness (Ra) Measured according to JIS SO601. That is, a stylus type surface roughness meter (SURFCOM 3B) manufactured by Tokyo Seimitsu Co., Ltd.
), draw a film surface roughness curve on the chart under the conditions of a needle radius of 2μ and a load of 0.07g, and measure the length L from the obtained film surface roughness curve in the direction of its center line.
With the center line of this extracted portion as the X axis and the vertical magnification direction as the Y axis, a roughness curve Y = f <
＞, the value given by the following formula (Ra: μm
) is defined as the film surface roughness.

Ra= (1/L) f l f (X) I
dx0 In the present invention, the reference length is 0. Eight samples were measured at 25 mffl, and Ra was expressed as the average value of five samples, excluding three samples from the largest value.

5. Film transparency (haze) Poic Hazemeter S manufactured by Nippon Seimitsu Kogaku ■
EP-} Measured with IS-D1.

Comparative Example 1 Polyethylene terephthalate, which does not contain any inorganic filler and has an intrinsic viscosity of 0.65 measured in Orthophenol at 25°C, was extruded from a die using an extruder, and electrostatic charge was applied on a drum cooled to 40°C. This was then extruded into a 1050 μm thick film by 3 steps in the longitudinal direction on a metal roll heated to 93°C.
It was stretched 6 times. Next, it was introduced into a tenter and passed through a 98°C preheating zone, stretched 3.9 times in the transverse direction at 105°C, and further heat-set at 225°C for 6.3 seconds to complete the crystal orientation. While slitting, winding was performed at a winding tension of 9.8 kg to a width of 500 mm. The final film had an average thickness of 75 μm.

Wrinkles occurred in the film roll due to poor mutual sliding between the films. Once these wrinkles occur, they propagate and concentrate one after another to the surface layer, resulting in a roll that is hard at one end of the roll and soft at the center, which is completely unsuitable for a product.

4. Set the winding tension to the extreme. Although it was rolled up at 66 kg, in addition to the edges being uneven, wrinkles were also observed, and a perfect product could not be obtained. The properties of this film are shown in Table 1.

Example 1 (A) Acrylic water dispersion "Acrisol A08" (manufactured by Nippon Carbide ■) 30 parts (as non-volatile component), (B
) Copolymerized polyester resin aqueous dispersion “Pess Resin 200
0J (manufactured by Takamatsu Yushi ■) 28 parts, (C) average particle size 0.
03 μm silicon oxide aqueous dispersion 10 parts, (D) Newc
28 parts of ol271A (manufactured by Nippon Nyukazai ■), and polyoxyethylene noninolepheni! Leatere rNS 2
08.5J (manufactured by NOF ■) was diluted and dissolved in ion-exchanged water to prepare a coating solution with a solid content concentration of 2% by weight.

In the same method for producing a biaxially stretched film as in Comparative Example 1, the above coating liquid was uniformly applied on one side of the uniaxially stretched film after longitudinal stretching using the kiss coating method at a position immediately before entering the tenter. .

The average coating amount at this time was approximately 4 g wet per 1 uniaxially stretched film (this amount corresponds to approximately 0.02 g per 1 resist for the biaxially stretched film described below).
. The uniaxially stretched film coated on one side was introduced into a tenter, passed through a 98°C preheating zone, stretched 3.9 times in the transverse direction at 105°C, and further heat-set at 225°C.

The properties of this film are shown in Table 1.

Examples 2 to 6 Antistatic polyester films were obtained in exactly the same manner as in Example 1, except that a coating solution having the composition shown in Table 2 was prepared.

Its characteristics are shown in Table 1.

Table 2 Acrylic emulsion (1); Methyl methacrylate/ethyl acrylate/N-methylol acrylamide = 50/45/5 (mol%) Acrylic emulsion (2); Methyl methacrylate/ethyl acrylate/methacrylamide = 45/47/8 (mol%) As agent (1); Methyl methacrylate/acrylonitrile/Na methacrylsulfonate = 49/8/43 (mol%
) AS agent (2); Methyl methacrylate/ethyl acrylate}/2-N
a Sulfoethyl methacrylate = 51/24/25
(mol%).

As is clear from Table 1, the polyester film of the present invention is transparent, has good antistatic properties, and also has slip properties.

Claims (1)

[Claims] 1. On at least one side of the polyester film, (A)
Acrylic resin, (B) copolymerized polyester resin, (C
) An antistatic polyester film comprising a thin layer comprising fine particles having an average particle size of 0.5 μm or less and (D) an antistatic agent. 2. The amount of component (A) is 0.1 relative to the amount of component (B).
The antistatic polyester film according to claim 1, wherein the antistatic polyester film is 5 times as large. 3. The total amount of component (A) and component (B), the amount of component (C), and the amount of component (D) are in the ratio of 20 to 80% by weight, 5 to 40% by weight, and 5 to 75% by weight. The antistatic polyester film according to claim 1.