JPS63154347A - Easily sliding polyester film - 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] <Industrial Field of Application> The present invention relates to a slippery polyester film, and more specifically to a slippery polyester film comprising a slippery thin layer of a methacrylate copolymer provided on at least one side of a polyester film. This invention relates to a slippery polyester film.

<Prior art> Polyester films, especially biaxially stretched films of polyethylene terephthalate, have excellent mechanical properties, heat resistance, and chemical resistance, so they can be used for magnetic tapes, photographic films, packaging films, metallizing films for capacitors, The demand for it as a material for electrical insulation films, OHP films, etc. has been growing particularly rapidly recently.

However, in order to smoothly produce polyester films and apply them to the above uses, it is necessary to improve the slipperiness of polyester films.

In other words, especially in the case of a polyester film with a flat surface, the slipperiness of the film is insufficient and the film cannot be rolled up.

This seriously impedes the work of winding, coating, slitting, etc., and causes troubles such as the occurrence of wrinkles in the winding and dust adsorption due to the generated static electricity. For example, when various molded products made by applying pressure molding or vacuum forming to unstretched or uniaxially stretched films of polyethylene terephthalate are stacked on top of each other, if the surface activity is insufficient, the molded products may slide smoothly into each other. Therefore, the ease of assembly line work in the processing process is significantly reduced.

Conventionally, as a means to improve the slipperiness of polyester films, H1i! However, it has been put into practical use to utilize the phenomenon in which the filler protrudes as minute protrusions on the film surface when the film thickness is reduced in the subsequent biaxial stretching process.

Similarly, as a slipperiness improvement technology using microprotrusions,
A method is also known in which a catalyst used during the polymerization of polyester is converted into particles that are insoluble in the polymer.

Although these methods have been successful in improving film slipperiness, the presence of microparticles within the film composition naturally reduces film clarity or introduces voids within the film composition. There are still issues that need to be improved, such as generation. In particular, the reduction in transparency or the formation of voids in polyester films used as materials for diazo films, metallized films, photographic films, or magnetic tapes and floppy disks that require flattening of the base surface due to high density is a serious problem. becomes.

On the other hand, unlike the above method in which microparticles are added to polyester to form microprotrusions on the film surface, a method in which a specific coating liquid is applied to both sides of a film made from polyester that does not contain such microparticles, A method has been proposed in which a worm-like film structure is formed on both sides of the film to impart slipperiness to the film.

Although this method uses a specific coating solution containing at least one of silicone or cellulose resin and a water-soluble polymer compound, fine particles are added to the polyester in order to impart slipperiness to the film through post-treatment. This is different from the method of imparting slipperiness to the film.

However, the water-soluble polymer that creates this worm-like treated surface has poor adhesion to the polyester film, and a new problem has arisen in which part of the treated layer is scraped off during the coating process or during turning. .

<Object of the Invention> The object of the present invention is to solve this problem, to provide a polyester film with excellent adhesion between the polyester film and the easily slippery thin layer, and to provide a film in which the easily slippery thin layer has self-fold-like fine irregularities. The object of the present invention is to provide a polyester film that exhibits excellent slipperiness and preferably has excellent durability.

<Configuration/Effects of the Invention> According to the present invention, an object of the present invention is to provide methyl methacrylate (A) on at least one side of a polyester film.
, ethyl methacrylate (B) and a vinyl monomer (C) copolymerizable with these, and the quantitative ratio of these is represented by the following formula +11. ! 2]1 ku [A ko / [B]
≦9...(1)0.
75 < ((1,5[A] + [B] )/([A
]+[B]+[C]))≦1,415...('2J
This is achieved by a slippery polyester film provided with a slippery thin layer of a methacrylate copolymer that satisfies the above requirements.

The slippery layer 1 forms a continuous layer with respect to the polyester film, and has self-fold-like fine irregularities formed on the surface (the side opposite to the polyester film). An example of such a surface condition is shown in FIGS. 1 and 2. FIG. 1 is an enlarged plan view, and FIG. 2 is an enlarged sectional view. In Figure 1, the blacked out areas indicate the convex parts of fine irregularities.
White areas indicate recesses or continuous layer parts. Further, the convex portion is long in the mechanical axis direction (longitudinal direction) of the polyester film and forms pleats.

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. Specific examples of such polyesters include polyethylene terephthalate,
Polyethylene isophthalate, polybutylene terephthalate.

Examples include poly(1,4-cyclohexylene dimethylene terephthalate) and polyethylene-2,6-naphthalene dicarboxylate, and also include copolymers thereof or blends of these with small proportions of other resins.

The polyester film of the present invention can be 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. As for this polyester film, the heat of crystal fusion was measured using a differential scanning calorimeter at [10°C] in a nitrogen stream.
The value measured at a heating rate of /min] is usually 4 C.
It is preferable that the crystal orientation is such that it exhibits al/SF or higher.

In the present invention, a slippery vIJ is applied on a polyester film.
The methacrylate copolymers forming the layer are methyl methacrylate (A) and ethyl methacrylate (B).
and a vinyl monomer (C) copolymerizable with these, and the quantitative ratio of these is the following formula (11i2) % formula % (1) where [A] is the above (A>component) in the polymer. mole%
.

[B] is the mole% of the component (B) in the polymer.

[C] is the mol% of the component (C) in the polymer It is a methacrylate copolymer that satisfies the following.

In the above formula, if [A]/[B] is less than 1, it will not be possible to exhibit easy sliding properties, while if [A]/[B] exceeds 9, adhesiveness and flexibility will decrease, The abrasion resistance deteriorates, and (1.5[A] + [B])/([A
]+[B]+[C]) (hereinafter referred to as X) is 0.75 or less, the blocking resistance decreases, while when X is 1.4
If it exceeds 15, it becomes difficult to form a uniform coating solution, especially a uniform aqueous coating solution of 11, which is not preferable.

X is thicker than 0.94 (preferably 1.38 or less).

Examples of the vinyl monomer (C) include alkyl acrylate (the alkyl group is a methyl group).

Ethyl33. n-propyl group, isopropyl group, n-butyl group, isobutyl 1. t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); alkyl methacrylate (alkyl group is C3 or higher, n-butyl group, isopropyl group);

(n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); Containing monomer; acrylamide, methacrylamide, N-methylmethacrylamide, N-methylacrylamide,
N-methylolacrylamide, N-methylolmethacrylamide, N-alkoxymethyl(meth)acrylamide (methyl group as alkyl group).

ethyl group, propyl group, butyl group, isobutyl group, etc.),
Amide group-containing monomers such as N,N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide, etc.; N,N-diethylaminoethyl acrylate, N,N-diethylaminoethyl methacrylate Epoxy group-containing monomers such as nigericidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, etc.; styrene sulfonic acid, vinyl sulfonic acid and their salts (sodium salt, potassium salt, ammonium Monomers containing sulfonic acid groups or their salts such as crotonic acid, itaconic acid, acrylic acid, maleic acid, fumaric acid and their salts (sodium salts, potassium salts, ammonium salt.

Monomers containing carboxyl groups or salts thereof such as tertiary amino acids (tertiary amino acids, etc.); Monomers containing M anhydrides such as maleic anhydride, itaconic anhydride, etc.; Others, vinyl isocyanate, allyl isocyanate, Examples include styrene, vinyl methyl ether, vinyl ethyl ether, vinyltris alkoxysilane, alkyl maleic acid monoester, acrylonitrile, methacrylonitrile, alkyl itanconic acid monoester, vinylidene chloride, vinyl acetate, vinyl chloride, and the like. These can be used alone or in combination of two or more.

Among these, hydroxyl groups, amide groups, carboxyl groups, or their salts (sodium salts, potassium salts) , ammonium salt, tertiary amine salt, etc.) are preferred. Furthermore, from the point of introducing a crosslinked structure into the polymer, N-methylol (meth)acrylamide, N-alkoxymethyl (meth)acrylamide, glycidyl (meth)acrylate, (meth)acrylic acid, 2-hydroxyethyl (meth)acrylamide, Alkoxy groups, such as acrylates,
Methylol group, carboxyl group, water! ! Those having one functional group and/or an epoxy group are preferred. Examples of combinations of two types of functional groups include a methylol group and a carboxyl group, a glycidyl group and a hydroxyl group, a glycidyl group and a carboxyl group, and the like. The precursor methacrylate copolymer having these two types of functional groups is a self-crosslinking type. Further, the precursor methacrylate copolymer having one type of functional group is preferably used in combination with a compound or oligomer thereof (thermosetting agent) having a group that reacts with the functional group. As such a thermosetting agent, for example, methylolated melamine resin, epoxy compound, aziridine compound, polyvalent metal compound, etc. are preferably used. These amounts are 1 to 30% of the resin solid content forming the easily slippery thin layer, and more preferably 5 to 30%.
15% by weight is preferred.

The easily slippery thin layer in the present invention can be formed by applying a coating liquid, preferably an aqueous liquid, containing the components for forming the thin layer onto a polyester film, and drying and curing the coating liquid. When the thin layer-forming component is of a crosslinking type, it is preferable to carry out a crosslinking reaction in the dry curing treatment described above.

The coating liquid is preferably an aqueous liquid such as an aqueous solution or a water emulsion liquid. This aqueous liquid may contain some amount of organic solvent to stabilize the dispersion of the solid components.

When an aqueous liquid is used, the precursor methacrylate copolymer forming the methacrylate copolymer or crosslinked copolymer is a hydrophilic polymer. This hydrophilicity can be judged by whether the polymer dissolves in an aqueous medium or forms a homogeneous emulsion.

The aqueous liquid can be produced by any known method.

For example, to illustrate an emulsion polymerization method of components (A), (B), and (C) in an aqueous dispersion system, an emulsion dispersant (
(a surfactant such as sodium dodecylbenzenesulfonate), a water-soluble polymerization initiator (a peroxide such as ammonium peroxide), a polymerization accelerator (a reducing agent such as sodium sulfite) are added as appropriate, and While stirring at a predetermined stirring speed at a temperature of (for example, 50 to 90 ° C.),
Add the monomer to a predetermined amount and 10 to 50% by weight, and once polymerization has started, add for a short time during medium I! l'i
Thereafter, the remaining monomers are added at a constant rate and emulsion polymerization is carried out under the same conditions for several hours, thereby producing an aqueous dispersion of the methacrylic copolymer (or its precursor). In this case, the addition m of the surfactant used in the reaction is preferably 5% by weight or less, more preferably 1 to 2% by weight, based on the monomer of the polymerization component. In this way, particles having an average particle size of 0.2 μm or less can be obtained.

Note that, if necessary, a thermosetting agent, a molecular weight regulator (mercaptans), a dispersion aid (polyvinyl alcohol, polymeric protective colloids such as human O-oxymethyl cellulose), etc. may be added.

In addition, a production method using so-called soap-free polymerization, which does not contain a reactive surfactant (1), may also be adopted.

The molecular weight of the methacrylic copolymer (thermoplastic type) or its precursor methacrylic copolymer (crosslinked type) dissolved or finely dispersed in the coating liquid is 1 to 2 million, and more preferably 50 to 2 million.
1.5 million is preferred. Further, it is preferable that such a polymer has a glass transition temperature of 40°C or higher, more preferably 50°C or higher. Further, a required amount of surfactant such as an anionic surfactant, a cationic surfactant, a nonionic surfactant, etc. can be added to the coating liquid, particularly the aqueous liquid. As such a surfactant, the surface tension of the aqueous coating solution is 40 dy.
It is preferable to use a material that can drop to ne/cm or less and promotes wetting to a polyester film, 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,
Examples include quaternary ammonium chloride salts and alkylamine hydrochloric acids. Furthermore, within the range that does not eliminate the effects of the present invention, for example, antistatic agents, ultraviolet absorbers,
Other additives such as pigments, organic fillers, inorganic fillers, fit lubricants, antiblocking agents, etc. can be mixed.

The coating may be carried out in a normal coating process, that is, in a process in which %N is coated on a two-wheel stretched and heat-set polyester film, separate from the film manufacturing process.

However, this process tends to trap 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 coating liquid to one or both sides of the polyester film before the crystal orientation is completed during this step.

Here, the polyester film before the completion of crystal orientation refers to an unstretched film obtained by thermally melting polyester and forming it into a film as it is; Uniaxially stretched film oriented in one direction; biaxially stretched film).

The solid content concentration of the coating liquid is usually 30% by weight or less, and more preferably 10% by weight or less. The coating amount is 0.5 to 20 g per 1 TIt of running film, and further 1 to 1 g.
0g is preferred.

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

For example, roll coating method, gravure coating method, roll plush method, spray coating method, air knife coating method,
It is preferable to apply an impregnation method, a curtain coating method, etc. alone or in combination.

The polyester film coated with the coating liquid and before crystal orientation is completed is dried and subjected to processes such as stretching and heat setting. For example, a longitudinally-axially stretched polyester film coated with an aqueous liquid is guided into a stenter and then laterally stretched and heat-set. During this time, the coating solution dries and forms a film having self-folded fine irregularities on the film. Drying is preferably carried out before or during stretching.

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

The easily slippery polyester film of the present invention has excellent adhesion between the easily slippery thin layer and the polyester film, the thin layer does not scrape off, and the slippery polyester film of the present invention has a flat surface (e.g., surface roughness Ra of 0.02μ or less). ), it has excellent anti-blocking properties and rollability, making it particularly useful as a base for high-density magnetic tapes, floppy disks, etc.

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

In addition, "part" in an example means "weight part j.

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

10 Surface slipperiness Slipperiness The static FJ friction coefficient of single-layer surfaces under a load of 1 kg is measured at a temperature of 20° C. and a humidity of 60% RH using a slippery measurement tester manufactured by Toyo Tester Co., Ltd.

2. Blocking property Easy-slip thin layer surfaces were put together and then cut into 10α x 15 cm squares. A load of 6 kg/aj was applied to this in an atmosphere of 55°C x 88% RH for 17 hours, and then this 10 CIR width was peeled off. Measure intensity. The peeling speed at this time is 10
0m/min.

3. Using a dropper, drop 5 drops (approximately 1 cc) of tetrahydrofuran on the slippery thin layer surface of the slippery polyester film with or without a crosslinked structure,
A gauze is placed on top of the gauze, a weight of 200 g is placed on top of the gauze, and the gauze is moved at a speed of about 11,000 a/min.

After drying in hot water, compare the samples that were not treated with tetrahydrofuran with those that were treated with 400x interference micrographs to see the changes in the thin layer surface.

This state of change is expressed by the following ranks.

Thin layer has almost disappeared: × (There is no cross-linked structure) Thin layer morphology has changed: Δ (There is a cross-linked structure, but its proportion is small) The thin layer morphology has almost changed. Absent: 0 (sufficient crosslinked structure) 4. Surface roughness (Ra) Measured according to JIS 80601. That is, a stylus type surface roughness meter (SURFCOM) manufactured by Tokyo Seimitsu Co., Ltd.
3B), draw a film surface roughness curve on the chart under the conditions of a needle radius of 2μ and a load of 0.079, and measure a portion of length L from the obtained film surface roughness curve in the direction of its center line. , and draw the center line of this extracted part to
The roughness curve Y=f(
x), the value (Ra:
μm) is defined as the film surface roughness.

Ra -1/L/, I r (x) ldx In the present invention, 8111 il was measured using a reference length of 0.25 MR, and Ra is expressed as the average value of five values excluding three from the largest value.

Examples 1 to 4 and Comparative Examples 1 to 3 Intrinsic viscosity measured in O-chlorophenol at 25°C 0
．． 65 polyethylene terephthalate (30 pp lubricant
m containing) was melt-extruded onto a rotating cooling drum maintained at 20°C to obtain an unstretched film with a thickness of 950 μm, which was first stretched 3.5 times in the machine axis direction, and then mixed with 90 parts of the aqueous resin component shown in Table 1. An aqueous liquid containing 10 parts of a nonionic surfactant (polyoxyethylene nonylphenyl ether) was applied to both sides of the uniaxially stretched film by a kiss coating method. Continued 1
The film was stretched 3.9 times in the transverse direction at 05° C. and further heat-treated at 210° C. to obtain a coated polyester film having a thickness of 75 μm and slipping on both sides. The average coating interval at this time is 50% in terms of solid content.
■／It was the butt.

The properties of this polyester film are shown in Table 1.

Furthermore, as Comparative Examples 1 and 2, the performance of polyester films without easy WJB (30 pDl of lubricant, 0.3 wt%) is also shown in Table 1.

From Table 1, it is clear that the polyester film of the present invention is flat and easily slippery, and also has good anti-blocking properties.

Example 5 Water-based resin [MMA/EMA/MAA/HEMA-80/
18/5/3 (molar ratio)] 78 parts, 10 parts of methylated melamine resin Sumitex Resin M3.

Example 1 except that an aqueous solution containing 2 parts of Sumitex Accelerator ACX and 10 parts of a surfactant was used.
A polyester film coated with an easy-slip layer was obtained in the same manner as described above. This film has a surface roughness Ra of 0.007μ and a coefficient of static friction (μS) of 0.45, and is a flat and easily slippery film.

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view of a slippery polyester film, and FIG. 2 is an enlarged sectional view of the film. In FIG. 2, 1 is a base film, and 2 is an easily slippery layer. Figure 1

Claims (1)

[Claims] 1. At least one side of the polyester film contains methyl methacrylate (A) and ethyl methacrylate (B).
) and a vinyl monomer (C) copolymerizable with these, and the quantitative ratio of these is the following formula (1), (2) 1<[A]/[B]≦9...(1) 0.75 <((1.5[A]+[B])/([A]+[B]+[C]))≦1.415...(2) [In the formula, [A] represents the above-mentioned ( A) Mol% of components
, [B] is the mol% of the component (B) in the polymer, and [C] is the mol% of the component (C) in the polymer. An easily slippery polyester film. 2. The easily slippery polyester film according to claim 1, wherein the methacrylate copolymer has a crosslinked structure.